Air guide structure for saddle type vehicle

ABSTRACT

An air guide structure for a saddle type vehicle by which influence of exhaust air from a radiator on a fuel tank can be reduced effectively. A fuel tank is formed with a tank extension section extending to above the upper end of the radiator. A front wall of the tank extension section is inclined forward by obliquely extending rearwardly downward. A front lower cover disposed forwardly of the radiator and rearwardly of a front wheel is provided. The front lower cover is provided with a radiator opening section having a plurality of openings for guiding airflow to the radiator, and with a fuel tank opening section for guiding the airflow to the fuel tank inclusive of the tank extension section.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an air guide structure for a saddletype vehicle in which a fuel tank and a radiator located forwardly ofthe fuel tank are provided in a center tunnel provided between left andright step floors.

2. Description of Related Art

As a saddle type vehicle having a center tunnel under an area between ahead pipe constituting a body frame and a seat and in which step floorsare provided on vehicle-width-directionally both sides of the centertunnel, there has been known one wherein a fuel tank is disposed in thecenter tunnel and a radiator is disposed forwardly of the fuel tank(refer to, for example, Japanese Patent Laid-Open No. 2008-213520).

In Japanese Patent Laid-Open No. 2008-213520, the radiator is disposedforwardly of the fuel tank, so that exhaust air having passed across theradiator to cool the radiator is raised in temperature, and wouldinfluence the ambient temperature in the periphery of the fuel tank. Inview of this, it may be contemplated to take a countermeasure such asproviding a heat insulating plate between the fuel tank and theradiator. In this case, a structure for reducing more effectively theinfluence of exhaust air from the radiator on the fuel tank is demanded.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of theabove-mentioned circumstances. Accordingly, it is an object of thepresent invention to provide an air guide structure for a saddle typevehicle by which it is possible to reduce more effectively the influenceof exhaust air from a radiator on a fuel tank.

In order to solve the above-mentioned problem, according to the presentinvention, there is provided an air guide structure for a saddle typevehicle including a head pipe turnably supporting a steering system andconstituting a front portion of a body frame, a seat disposed rearwardlyof the head pipe, a center tunnel provided between the head pipe and theseat, step floors provided on the left and right sides of the centertunnel, a fuel tank disposed in the center tunnel, and a radiatordisposed forwardly of the fuel tank in the center tunnel, wherein thefuel tank is provided with a tank extension section that extends toabove an upper end of the radiator, a front wall of the tank extensionsection is inclined forward by obliquely extending rearwardly downward,a front lower cover is disposed forwardly of the radiator and rearwardlyof a front wheel, and the front lower cover is provided with a radiatoropening section for guiding airflow (attendant on the traveling of thevehicle) to the radiator and with a fuel tank opening section forguiding the airflow to the fuel tank inclusive of the tank extensionsection.

According to this configuration, the front lower cover is provided withthe fuel tank opening section separately from the radiator openingsection. This ensures that the airflow can be guided to the fuel tankvia the fuel tank opening section, and that fresh air other than theradiator exhaust air can be guided to an area between the radiator andthe fuel tank by utilizing the front wall of the tank extension section.Therefore, the influence of the exhaust air from the radiator on thefuel tank can be reduced more effectively.

In addition, in the above-mentioned configuration, a configuration maybe adopted wherein a heat insulation guide that covers a part of thefront wall of the fuel tank to avoid thermal influence of the exhaustair from the radiator is provided between the fuel tank and theradiator, and a predetermined clearance is provided between the heatinsulation guide and the fuel tank over a range from an upper end to alower end of the heat insulation guide. According to this configuration,not only the front wall of the fuel tank is covered but also thepredetermined clearance is provided between the heat insulation guideand the fuel tank. This ensures that the airflow introduced via thefront lower cover is guided into an area between the heat insulationguide and the fuel tank, whereby a heat-insulating effect can beenhanced and thermal influence on the fuel tank can be reduced further.

Besides, in the above-mentioned configuration, the upper end of the heatinsulation guide may be disposed below the upper end of the radiator andabove a vertical-directionally central position of the radiator. Thisconfiguration is advantageous as follows. If, for example, the heatinsulation guide is disposed above the upper end of the radiator, theclearance between the radiator and the fuel tank must be enlarged, sincethe front wall of the fuel tank is inclined forward. According to thelust-mentioned configuration, on the other hand, the upper end of theheat insulation guide is disposed below the upper end of the radiator,so that the spacing between the radiator and the fuel tank can bereduced. Consequently, the vehicle can be made compact in itslongitudinal direction (front-rear direction).

In addition, since the upper end of the heat insulation guide isdisposed below the upper end of the radiator, the exhaust air from theradiator may be considered to enter the area between the heat insulationguide and the fuel tank via the upper end of the heat insulation guide.Since the upper end of the heat insulation guide is provided above thevertical-directionally central position of the radiator, however, freshair (other than the exhaust air from the radiator) introduced via thegap between the radiator upper end and the fuel tank can restrain theradiator exhaust air from being introduced into the area between theheat insulation guide and the fuel tank by way of the heat insulationguide upper end. As a result, the influence of the exhaust air from theradiator can be minimized.

Further, with the upper end of the heat insulation guide disposed belowthe upper end of the radiator, the clearance between the radiator upperend and the fuel tank can be reduced. This contributes to realization ofa more compact vehicle. Moreover, this configuration ensures that theflow velocity of the fresh air passing through the clearance between theradiator upper end and the fuel tank can be enhanced, so that the freshair can be easily introduced into the clearance between the heatinsulation guide and the fuel tank.

Besides, in the above-mentioned configuration, the heat insulation guidemay be provided with longitudinal fin parts projecting forward, onvehicle-width-directionally both sides, so as to restrain exhaust airfrom the radiator from flowing to vehicle-width-directionally outersides of the longitudinal fin parts. This configuration makes itpossible to collect the radiator exhaust air to thevehicle-width-directionally inner side of the longitudinal fin parts,and to suppress more effectively the thermal influence of the radiatorexhaust air on the fuel tank.

In addition, in the above-mentioned configuration, a configuration maybe adopted wherein the fuel tank is covered with an under cover on thelower side thereof, the under cover is provided with an air guide wallextending toward the radiator side, and an upper end of the air guidewall and a lower end of the heat insulation guide are disposed proximateto each other in the vertical direction (height direction). According tothis configuration, the upper end of the air guide wall and the lowerend of the heat insulation guide are disposed proximate to each other.This ensures that a radiator exhaust air passage with a large area canbe formed by the air guide wall and the heat insulation guide, whilerestraining water or the like from entering via the gap between the airguide wall and the heat insulation guide. The air guide wall and theheat insulation guide cooperate with each other to cause the radiatorexhaust air to flow down from the rear side of the radiator along theheat insulation guide and the front surface of the air guide wall, sothat the radiator exhaust air is discharged to the lower side of theunder cover. In addition, fresh air can be guided along back surfaces ofthe heat insulation guide and the air guide wall to flow to the lowersurface side of the fuel tank. Thus, the air introduced can bedistributed to front and rear two layers of flow, with the heatinsulation guide and the air guide wall as a boundary. In the one-sidelayer of flow, exhaust of the radiator exhaust air is conducted, whileheat insulation by the fresh air is conducted in the other-side layer offlow. By both of these functions, it is made possible to reduce moreeffectively the thermal influence on the fuel tank.

Besides, in the above-mentioned configuration, the upper end of the airguide wall and the lower end of the heat insulation guide may bedisposed with a predetermined clearance therebetween. This configurationensures that the air guide wall and the heat insulation guide define thepredetermined clearance therebetween and are therefore not connectedwith each other, although they are disposed proximate to each other.Therefore, a step of assembling the air guide wall and the heatinsulation guide in the inside of the body cover can be abolished, andproductivity can be enhanced thereby.

In addition, in the above-mentioned configuration, a configuration maybe adopted wherein under side covers are provided onvehicle-width-directionally both sides of the under cover, and theoutside ends of the under cover and the inside ends of the under sidecovers are disposed separate from each other. This configuration ensuresthat the fresh air guided into an area between the under cover and thelower surface of the fuel tank can be discharged via clearances betweenthe under cover and the under side covers, so that a flow rate of thefresh air can be secured. Consequently, the thermal influence on thefuel tank can be reduced more effectively.

Besides, in the above-mentioned configuration, the outside ends of theunder cover and the inside ends of the under side covers may be sodisposed as to overlap with each other in plan view. According to thisconfiguration, it is possible to lower the possibility of a situationwherein water and the like splashed from the front wheel might enter theinside of the under cover and the under side covers from the lower sideof the vehicle body, since the outside ends of the under cover and theinside ends of the under side covers are spaced apart in the verticaldirection.

According to the present invention, the fuel tank is formed with thetank extension section extending upward to above the upper end of theradiator, and the front wall of the tank extension section is inclinedforward by obliquely extending rearwardly downward. Besides, the frontlower cover is disposed forwardly of the radiator and rearwardly of thefront wheel, and the front lower cover is provided with the radiatoropening section for guiding airflow to the radiator and with the fueltank opening section for guiding the airflow to the fuel tank inclusiveof the tank extension section. Since the front lower cover is providedwith the fuel tank opening section separately from the radiator opening,it is made possible to introduce the airflow to the fuel tank via thefuel tank opening section, and to guide fresh air (other than theradiator exhaust air) into the area between the radiator and the fueltank through utilizing the front wall of the tank extension section.Therefore, the influence of the radiator exhaust air on the fuel tankcan be reduced further effectively.

In addition, the heat insulation guide, which covers a part of the frontwall of the fuel tank to avoid thermal influence of the radiator exhaustair, is provided between the fuel tank and the radiator, and thepredetermined clearance is provided between the heat insulation guideand the fuel tank over the range from the upper end to the lower end ofthe heat insulation guide. Thus, not only the front wall of the fueltank is covered but also the predetermined clearance is provided betweenthe heat insulation guide and the fuel tank. This ensures that theairflow introduced via the front lower cover is guided into the areabetween the heat insulation guide and the fuel tank, whereby aheat-insulating effect can be enhanced and thermal influence on the fueltank can be further reduced.

Besides, the upper end of the heat insulation guide is disposed belowthe upper end of the radiator and above the vertical-directionallycentral position of the radiator, which is advantageous as follows. If,for example, the heat insulation guide is disposed above the upper endof the radiator, the clearance between the radiator and the fuel tankmust be enlarged because the front wall of the fuel tank is inclinedforward. When the upper end of the heat insulation guide is disposedbelow the upper end of the radiator, on the other hand, the spacingbetween the radiator and the fuel tank can be reduced. This permits thevehicle to be compacter in its longitudinal direction.

Since the upper end of the heat insulation guide is disposed below theupper end of the radiator, exhaust air from the radiator may beconsidered to enter into the gap between the heat insulation guide andthe fuel tank by way of the upper end of the heat insulation guide.Since the upper end of the heat insulation guide is provided above thevertical-directionally central position of the radiator, however, freshair (other than the exhaust air from the radiator) introduced via thespacing between the radiator upper end and the fuel tank can restrainthe radiator exhaust air from being introduced into the gap between theheat insulation guide and the fuel tank by way of the upper end of theheat insulation guide. Therefore, the influence of the exhaust air fromthe radiator can be minimized.

Further, arrangement of the upper end of the heat insulation guide belowthe upper end of the radiator makes it possible to reduce the clearancebetween the radiator upper end and the fuel tank, which contributes torealization of a more compact vehicle. In addition, this configurationmakes it possible to enhance the flow velocity of the fresh air passingthrough the clearance between the radiator upper end and the fuel tank.Consequently, the fresh air can be easily guided into the clearancebetween the heat insulation guide and the fuel tank.

Besides, the heat insulation guide is provided with the longitudinal finparts projecting forward, on vehicle-width-directionally both sides, soas to restrain the radiator exhaust air from flowing to thevehicle-width-directionally outer sides of the longitudinal fin parts.Therefore, the radiator exhaust air can be collected to thevehicle-width-directionally inner side of the longitudinal fin parts,and the thermal influence of the radiator exhaust air on the fuel tankcan be suppressed more effectively.

In addition, the lower side of the fuel tank is covered with the undercover, the under cover is provided with the air guide wall extendingtoward the radiator side, and the upper end of the air guide wall andthe lower end of the heat insulation guide are disposed proximate toeach other in the vertical direction. This configuration ensures that aradiator exhaust air passage with a large area can be formed by the airguide wall and the heat insulation guide, while restraining water andthe like from entering via the gap between the air guide wall and theheat insulation guide. The air guide wall and the heat insulation guidecooperate with each other to cause the radiator exhaust air to flow downfrom the rear side of the radiator along the heat insulation guide andthe front surface of the air guide wall, to be discharged to the lowerside of the under cover. In addition, fresh air can be guided along backsurfaces of the heat insulation guide and the air guide wall to flow tothe lower surface side of the fuel tank. Thus, the air introduced can bedistributed to front and rear two layers of flow, with the heatinsulation guide and the air guide wall as a boundary. In the one-sidelayer of flow, exhaust of the radiator exhaust air is conducted, whileheat insulation by the fresh air is conducted in the other-side layer offlow. By both of these functions, it is made possible to reduce moreeffectively the thermal influence on the fuel tank.

Besides, since the upper end of the air guide wall and the lower end ofthe heat insulation guide are disposed with the predetermined clearancetherebetween, the air guide wall and the heat insulation guide definethe predetermined clearance therebetween and are therefore notinterconnected, although they are disposed proximate to each other. Thismakes it possible to abolish a step of assembling the air guide wall andthe heat insulation guide in the inside of the body cover, and therebyto enhance productivity.

In addition, the under side covers are provided onvehicle-width-directionally both sides of the under cover, and theoutside ends of the under cover and the inside ends of the under sidecovers are disposed apart from each other. This ensures that the freshair guided by the air guide wall into the area between the under coverand the fuel tank lower surface can be discharged via the clearancesbetween the under cover and the under side covers. Since a flow rate ofthe fresh air is thus secured, thermal influence on the fuel tank can bereduced more effectively.

Besides, the outside ends of the under cover and the inside ends of theunder side covers are disposed to overlap with each other. This makes itpossible to lower the possibility of a situation in which water and thelike splashed by the front wheel might enter the inside of the undercover and the under side covers from the lower side of the vehicle body,since the outside ends of the under cover and the inside ends of theunder side covers are spaced apart in the vertical direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a left side view of a motorcycle according to an embodiment ofthe present invention.

FIG. 2 is a left side view showing the internal structure of themotorcycle.

FIG. 3 is a perspective view of a body frame.

FIG. 4 is a left side view of the body frame.

FIG. 5 is an essential part left side view of the motorcycle.

FIG. 6 is an essential part sectional view of the motorcycle, with apart of the body frame omitted.

FIG. 7 is an essential part sectional view showing a radiator, a fueltank and the surroundings thereof.

FIG. 8 is an essential part sectional view showing a front lower portionof the motorcycle.

FIGS. 9A-C show illustrations of an air exhaust guide.

FIGS. 10A-C show illustrations of an under cover.

FIG. 11 is an essential part front view of the motorcycle from which abody cover has been removed.

FIG. 12 is an essential part front view of the motorcycle.

FIG. 13 is a perspective view of the body frame and the surroundingsthereof.

FIG. 14 is an essential part right side view of the motorcycle fromwhich a part of the body cover has been removed.

FIG. 15 is an essential part bottom view of a bottom portion of themotorcycle.

FIG. 16 is an essential part bottom view of a vehicle body frontportion.

FIG. 17 is an essential part sectional view of the vehicle body frontportion.

FIG. 18 is a sectional view of a left lower portion of the vehicle bodyfront portion.

FIG. 19 is a sectional view taken along line XIX-XIX of FIG. 15.

FIG. 20 is an operation diagram illustrating flows of air inside thebody cover.

FIG. 21 is an operation diagram showing the flow of exhaust air from theradiator.

FIG. 22 is an operation diagram showing the flow of air in a lowerportion of the body cover.

FIG. 23 is an operation diagram illustrating the operation of a lift-upsupport part of a front lower cover.

FIG. 24 is an operation diagram illustrating the operation of a steppedpart in a rearward extension section of the front lower cover.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, an embodiment of the present invention will be described below,referring to the drawings. Incidentally, in the following, suchdirections as the forward, rearward, leftward, rightward, upward anddownward directions will be the same as those with respect to thevehicle body, unless otherwise specified. In addition, reference sign FRshown in the drawings indicates the front side of the vehicle body,reference sign UP the upper side of the vehicle body, and reference signLE the left side of the vehicle body.

FIG. 1 is a left side view of a motorcycle 1 according to thisembodiment of the present invention.

The motorcycle 1 (saddle type vehicle) is a motor scooter type vehiclehaving left and right low-floor step floors 68 on which to put the feetof the rider seated on a seat 10. A front wheel 2 is provided forwardlyof a body frame F (see FIG. 2), and a rear wheel 3 as a driving wheel issupported through an axle on a unit swing engine U (unit swing powerunit) disposed at a rear portion of the vehicle. The body frame F iscovered with a resin-made body cover C.

FIG. 2 is a left side view showing the internal structure of themotorcycle 1, and FIG. 3 is a perspective view of the body frame F.Here, in FIG. 2, a state wherein a part of the body cover C has beenremoved is shown.

As shown in FIGS. 2 and 3, the body frame F has a plurality of metallictubes and pipes interconnected by welding. A main frame 11 includes: ahead pipe 12 provided at a front portion of the main frame 11; left andright down tubes 13, 13 extending rearwardly downward from the head pipe12, then extending rearward roughly horizontally, and extendingrearwardly upward at rear portions thereof; left and right seat rails14, 14 extending rearwardly upward from lower portions of the down tubes13, 13 to vehicle body rear portions; and left and right upper tubes 15,15 extending rearwardly downward over the down tubes 13, 13 from thehead pipe 12 and connected to the seat rails 14, 14.

The down tubes 13, 13 each include a downward extension section 70connected to the head pipe 12 at its front end and extending rearwardlydownward, a horizontal extension section 71 extending roughlyhorizontally rearward from the lower end of the downward extensionsection 70, and an oblique upward extension section 72 extendingrearwardly upward from the rear end of the horizontal extension section71.

As shown in FIG. 3, the main frame 11 is provided with cross membersthat interconnect the left and right frames. The cross members include:a front upper cross member 16 which interconnects upper portions of thedownward extension sections 70, 70 of the down tubes 13, 13; a frontcross member 17 that interconnects lower portions of the downwardextension sections 70, 70; a horizontal section cross member 18 thatinterconnects the horizontal extension sections 71, 71 of the down tubes13, 13; an upper cross member 19 that interconnects the upper tubes 15,15; an intermediate cross member 20 that interconnects the seat rails14, 14; and a rear cross member 21 that interconnects rear portions ofthe seat rails 14, 14. The horizontal section cross member 18 isconnected to the horizontal extension sections 71, 71 by bolting.

Left and right tandem step stays 22, 22 extending towardvehicle-width-directionally outer sides are provided at upper portionsof the oblique upward extension sections 72, 72 of the down tubes 13,13.

A cage-like front frame 24, which supports lights, the body cover C andthe like, is connected to a front surface of the head pipe 12.

Besides, left and right step frames 23L, 23R (reference sign 23L isshown in FIG. 2, while reference sign 23R is shown in FIG. 14), whichare connected to the down tubes 13, 13 and extend in the front-reardirection (vehicle longitudinal direction) so as to support the stepfloors 68 from below, are provided on the lateral outer sides of themain frame 11.

As shown in FIGS. 1 and 2, a steering system 260 for steering the frontwheel 2 includes a steering shaft (not shown) turnably supported on thehead pipe 12, and a handlebar 25 connected to an upper portion of thesteering shaft. The lower end of the steering shaft is connected to leftand right front forks 26, 26, the front wheel 2 is rotatably supportedon the lower ends of the front forks 26, 26 through an axle 2A, and issteered by an operation of the handlebar 25.

The unit swing engine U is of a unit swing type in which an engine E anda transmission case 51 with a belt-type continuously variabletransmission (not shown) housed therein are united together. The unitswing engine U functions also as a swing arm for supporting the rearwheel 3. The unit swing engine U is connected to rear portions of thedown tubes 13, 13 through link members 27 connected to its frontportions, and is vertically swingable about a pivot 28 provided on thelink members 27.

The engine E is a water-cooled four-cycle single-cylinder engine, and isso disposed that a cylinder axis thereof extends forward, roughlyhorizontally. The engine E has a configuration in which a cylinder 31(see FIG. 14) and a cylinder head 33 (see FIG. 14) are connected to afront surface of a crankcase 30 disposed at a front portion of the unitswing engine U (unit swing power unit).

The transmission case M extends rearward from a rear portion of thecrankcase 30 and on the left side of the rear wheel 3. An arm sectionextending rearward on the right side of the rear wheel 3 is provided ata rear portion of the crankcase 30. The rear wheel 3 is supported on anaxle 3A provided between a rear portion of the transmission case M and arear portion of the arm section. An output of the engine E istransmitted to the rear wheel 3 through the continuously variabletransmission.

Left and right rear suspensions 34, 34 (only reference sign 34 on theviewer's side is shown) are arranged between the rear end of thetransmission case M as well as the rear end of the arm section and theseat rails 14, 14.

At an upper surface of the transmission case M, an air cleaner box 35for sucking the outside air is provided. The air cleaner box 35 isconnected to a throttle body, which is connected to an intake port at anupper surface of the cylinder head 32, through a connecting tube (notshown).

An exhaust pipe 37 connected to an exhaust port at a lower surface ofthe cylinder head 32 extends rearward on the lower side of the engine E,and is connected to a muffler 38 (see FIG. 11) fixed to an outsidesurface of the arm section. A main stand 39 by which the vehicle can besupported in an upright state is provided at a lower portion of a rearpart of the transmission case M.

A fuel tank 40 for holding fuel for the engine E is formed to have itsfront surface along the downward extension sections 70 of the down tubes13 and have its rear surface along the upper tubes 15, in side view. Inthe vertical direction, the fuel tank 40 extends long vertically fromthe rear side of a lower portion of the head pipe 12 to the vicinity ofthe horizontal extension sections 71 of the down tubes 13. The fuel tank40 is disposed in a forwardly inclined state between the left and rightdown tubes 13, 13.

In a space under a front portion of the fuel tank 40 thus inclinedforwardly, a plate-like radiator 41, which cools cooling water for theengine E, is provided. A pair of cooling water pipes 42 forinterconnecting the radiator 41 and the engine E extend from a left sideportion of the radiator 41, extend rearward on the lower side of thestep frame 23L on the left side (one side) of the vehicle, and pass onthe inner side of the down tube 13, to be connected to the engine E. Aside stand 47 is attached to the horizontal extension section 71 on theleft side.

A reservoir tank 46 (see FIG. 14) for holding a portion of the coolingwater relevant to the radiator 41 is disposed under the step frame 23R(see FIG. 14) on the right side of the vehicle, on the rear side of theradiator 41. In addition, a canister 43 (see FIG. 14) for adsorption ofan evaporated fuel in the fuel tank 40 is provided under the step frame23R on the rear side of the reservoir tank 46.

A storage box 44 is disposed between the seat rails 14, 14, and extendsrearwardly upward along the seat rails 14, 14 from the vicinity of arear portion of the fuel tank 40 to the upper side of the transmissioncase M. The storage box 44 has a configuration wherein a front storagesection 44A disposed between the fuel tank 40 and the upward extensionsections 72 of the down tubes 13, and a rear storage section 44Bdisposed on the upper side of the unit swing engine U are integrallyformed by resin molding.

The storage box 44 is opening on the upper side over the overall lengththereof, and the opening is openably closed with the rider seat 10 (seeFIG. 1). The seat 10 has a front seat 10A on which to seat the rider,and a rear seat 10B which is formed to be a little higher than the frontseat 10A and on which to seat the pillion passenger.

A passenger grip 48 is fixed to rear portions of the seat rails 14, 14on the rear side of the storage box 44.

As shown in FIGS. 1 and 3, the body cover C includes: a front cover 50that covers the front side and the left and right sides of the head pipe12 and extends downward on the front side of the downward extensionsection 70; a front lower cover 51 (FIGS. 2 and 3) connected to a lowerportion of the front cover 50 and located rearwardly of the front wheel2; an upper cover 52 connected to an upper portion of the front cover 50on the lower side of the handlebar 25; an upper inner cover 53 that isconnected to left and right edge portions of the front cover 50 and bywhich the head pipe 12, the upper tubes 15, 15 and the downwardextension sections 70 are covered on the rear side and lateral sidesthereof; left and right lower inner covers 54, 54 that are connected tothe lower edge of the upper inner cover 50 and by which the upper tubes15, 15 and the downward extension sections 70 are covered; left andright step covers 55, 55 that are connected to a lower portion of thefront cover 50 and the lower edges of the lower inner covers 54, 54, andby which the left and right step frames 23L, 23R are covered on theupper side thereof; left and right front floor skirts 56, 56 that areconnected to a lower portion of the front cover 50 and lower portions ofthe step covers 55, 55, and by which the step frames 23L, 23R arecovered on lateral sides thereof; left and right rear floor skirts 57,57 that extend rearward in continuity with the front floor skirts 56, 56and that cover the down tubes 13, 13; an under cover 58 by which theleft and right horizontal extension section 71, 71 are covered on thelower side thereof; left and right body side covers 59, 59 that areconnected to the lower inner covers 54, 54 and rear portions of the stepcovers 55, 55 and by which the storage box 44 and the seat rails 14, 14are covered on lateral sides thereof under the seat 10; and a tail cover60 connected to rear portions of the body side covers 59, 59.

The left and right step floors 68 that receive the feet of the driverseated on the front seat 10A are formed at bottom portions of the leftand right step covers 55, 55.

The upper inner cover 53, the lower inner covers 54, 54 and the stepcovers 55, 55 are component parts constituting the center tunnel 250disposed on the lower side between the handlebar 25 and the seat 10.

At a front portion of the front cover 50, a windscreen 61 extendingrearwardly upward is provided. A headlamp 62 is provided at the frontend of the front cover 50, and left and right turn signal lamps 63 areprovided in continuity with an upper portion of the headlamp 62. Aplate-shaped garnish 64 is provided between the headlamp 62 and thewindscreen 61.

A front fender 65 by which the front wheel 2 is covered on the upperside thereof is provided on the front forks 26, 26. A rear fender 66 bywhich the rear wheel 3 is covered on the upper side thereof is providedunder the body side covers 59, 59.

Tiltable-type tandem steps 67 (see FIG. 1) that receive the feet of thepillion passenger seated on the rear seat 10B are supported by thetandem step stays 22, 22.

Now, the frame structure of the motorcycle 1 will be described in detailbelow.

As shown in FIGS. 3 and 4, each of the down tubes 13, 13 includes: thedownward extension section 70 connected at its front end to a lowerportion of the head pipe 12; a first bent section 73 bent rearward atthe lower end of the downward extension section 70; the horizontalextension section 71 extending rearward from the first bent section 73;a second bent section 74 formed at the rear end of the horizontalextension section 71 and bent rearwardly upward; and the oblique upwardextension section 72 extending rearwardly upward from the second bentsection 74 and connected at its rear end to the seat rail 14. Each ofthe down tubes 13, 13 is formed by bending a single continuous metallictube at the first bent section 73 and the second bent section 74 by abender. The spacing between the left and right down tubes 13, 13 isincreased along the rearward direction.

Left and right power unit support sections 85, 85 for supporting theunit swing engine U through the link members 27 are formed rearwardly ofthe second bent sections 74.

A stand stay 47A to which the side stand 47 is attached is mounted tothe horizontal extension section 71 on the left side, at a position on alateral side of the horizontal cross member 18.

The seat rails 14, 14 include: seat rail front sections 75 which areconnected at their front ends to rear surfaces of lower portions of thedownward extension sections 70 of the down tubes 13, 13 and extendrearwardly upward, and connected at their rear ends to the rear ends ofthe oblique upward extension sections 72; and seat rail rear sections 76extend from the rear ends of the seat rail front sections 75 to rearportions of the vehicle. The spacing between the left and right seatrails 14, 14 is increased along the rearward direction.

A rear second cross member 77 for interconnecting the seat rails 14, 14is provided forwardly of the rear cross member 21 between the seat railrear sections 76. The rear second cross member 77 and the rear crossmember 21 are interconnected by a reinforcement plate 78 extending inthe front-rear direction. In addition, a passenger grip stay 79 to whichthe passenger grip 48 is connected is provided on an upper surface ofeach seat rail rear section 76, whereas a box stay 80 to which thestorage box 44 is connected is provided at a front portion of each seatrail rear section 76.

The seat rail front sections 75, 75 are bent at seat rail bent sections75A at their rear portions. Of the seat rails 14, 14, the portionslocated rearwardly of the seat rail bent sections 75A are smaller inrearwardly rising angle than the portions located forwardly of the seatrail bent sections 75A.

The plate-shaped intermediate cross member 20 is provided between rearportions of the seat rail front sections 75, 75, and is locatedforwardly of rear connection parts 81 where the seat rails 14, 14 areconnected with the rear ends of the oblique upward extension sections72. Front connection parts 82 where the front ends of the seat railfront sections 75 are connected with the downward extension sections 70are provided at the lower ends of the downward extension sections 70.The front cross member 17 is formed in a U shape projecting forward, andis connected to front surfaces of the left and right front connectionparts 82, 82. Rearwardly of each of the front connection parts 82, aplate-shaped cross member 83 is provided that interconnects the seatrail front section 75 and the horizontal extension section 71 at aposition proximate to the front connection part 82. The plate-shapedcross member 83 is a flat plate extending vertically.

The upper tubes 15, 15 are connected at their front ends to an upperportion of the head pipe 12, extend rearwardly downward at a slighterinclination as compared with the downward extension sections 70, and areconnected at their rear ends to upper surfaces of the seat rail frontsections 75. The lower ends of the upper tubes 15, 15 are connected tothe seat rail front sections 75 at upper tube connection parts 84, whichare located rearwardly of the plate-shaped cross member 83. The spacingbetween the left and right upper tubes 15, 15 is increased along therearward direction. In addition, the upper tubes 15, 15 are located onthe inner side of the down tubes 13, 13 over the overall length thereof,in top plan view.

FIG. 5 is an essential part left side view of a motorcycle 1.

The fuel tank 40 is of a bisection structure composed of an upper tankhalf 40A and a lower tank half 40B. The upper tank half 40A and thelower tank half 40B are provided respectively with flanges 40 a and 40b, which are joined to each other. The flanges 40 a and 40 b at an upperportion of the fuel tank 40 are fastened to tank brackets 251 providedrespectively at the downward extension sections 70, 70 (only referencesign 70 on the viewer's side is shown) of the left and right down tubes13, 13 (only reference sign 13 on the viewer's side is shown) by bolts252 and nuts 253. A front wall 40 d of the fuel tank 40 is locatedforwardly of the downward extension sections 70 of the down tubes 13.

The radiator 41 is disposed forwardly of the fuel tank 40 and rearwardlyof the front lower cover 51, with its upper portion attached throughstays 256 to upper brackets 255 provided on the front upper cross member16, and with its lower portion attached to lower brackets 257 providedon the front cross member 17. In addition, the radiator 41 is disposedforwardly of the downward extension sections 70 of the down tubes 13.Further, in the vertical direction, the radiator 41 is disposed belowthe front upper cross member 16 and above the front cross member 17, andthe lower end 41 f of the radiator 41 is disposed above the first bentsections 73 of the down tubes 13.

A left tank section 41L provided in the radiator 41 is bisected intoupper and lower two tanks. The left tank section 41L is provided at itslower side surface with a lower hose connection port 41 a, to which alower radiator hose 261 is connected, and is provided at its upper rearsurface with an upper hose connection port 41 b, to which an upperradiator hose 262 is connected. Incidentally, reference sign 263Adenotes a lower pipe by which the lower radiator hose 261 is connectedto the engine E (see FIG. 2) side, and reference sign 263B denotes anupper pipe by which the upper radiator hose 262 is connected to theengine E (see FIG. 2) side. The lower pipe 263A and the upper pipe 263Bare component parts which constitute the cooling water pipes 42.

The lower radiator hose 261 and the lower pipe 263A are component partsthrough which cooling water from inside the engine E flows to a lowerportion of the left tank section 41L. The upper radiator hose 262 andthe upper pipe 263B are component parts through which the cooling waterflows from an upper portion of the left tank section 41L into the engineE. Thus, the lower radiator hose 261, the lower pipe 263A, the upperradiator hose 262, and the upper pipe 263B for the cooling water bywhich the radiator 41 and the engine E are interconnected, and arecollectively arranged on the left side of the body frame F. This layoutenhances assembleability and maintainability as compared with the casewhere these component parts are laid out distributedly on the left andright sides of the body frame F.

The front lower cover 51 includes a cover body 51 a curved to berearwardly protuberant and so disposed as to have its rear portionoverlapped with the front fender 65 in side view, and a rearwardextension section 51 b extending rearward from the lower end of thecover body 51 a. The cover body 51 a and the rearward extension section51 b are integrally molded, and are disposed rearwardly of the frontwheel 2. A front upper portion of the cover body 51 a is mounted to thefront upper cross member 16 side, while a rear end portion of therearward extension section 51 b is mounted to a lower surface of a lowercross member stay 264 attached to a lower portion of a front end part ofthe front cross member 17. The rearward extension section 51 b has itsrear end rearwardly of a lift-up part 51 p, which will be described indetail later. As above-mentioned, the front lower cover 51 is curved tobe rearwardly protuberant. This ensures that the front fender 65 can bedisposed inside the front lower cover 51 without any interference, andthat the front lower cover 51 can be disposed proximate to the frontfender 65 in the front-rear direction. Further, it is ensured thatairflow can be collected more easily into the inside of the front lowercover 51. As a result, the quantity of air flowing out toward theradiator 41 via a plurality of openings (described later) of the frontlower cover 51 can be increased, and the air flow velocity can beenhanced. Accordingly, cooling efficiency of the radiator 41 can beenhanced.

Rearwardly of the front lower cover 51, the under cover 58 is disposedso as to extend in the front-rear direction. The under cover 58 ismounted at its front portions to lower cross member side brackets 265(which are provided on the front cross member 17) by bolts 266, and ismounted at its rear portions to the power unit support sections 85(which are provided at the horizontal extension sections 71 of the downtubes 13) by bolts 268.

FIG. 6 is an essential part sectional view of the motorcycle 1, with apart of the body frame omitted.

The front wall 40 d of the fuel tank 40 is formed to be forwardlyinclined so as to obliquely extend downwardly rearward from its upperend. The forward inclination angle of the front wall 40 d relative tothe vertical is greater at an upper portion 40 e of the front wall 40 dlocated above the upper end 41 e of the radiator 41 than at a lowerportion 40 f of the front wall 40 d located below the upper end 41 e ofthe radiator 41. In addition, the upper end 40 j of the fuel tank 40 isdisposed above a horizontal line 270 that passes through the lower endof the head pipe 12.

The radiator 41 is provided to be vertical or is forwardly inclined sothat its lower end 41 f is located rearwardly of its upper end 41 e. Inaddition, the radiator 41 is disposed on the rear and lower side of thefront end 40 h of the fuel tank 40.

Besides, the forward inclination angles of the front wall 40 d of thefuel tank 40 relative to the vertical, at the upper portion 40 e and atthe lower portion 40 f, are greater than the forward inclination angleof the radiator 41 relative to the vertical.

A fan 271 by which exhaust air, or air having flowed across the radiator41, is forced to flow rearward and an electric motor 272 disposedrearwardly of the fan 271 to actuate the fan 271 are disposed rearwardlyof the radiator 41. In addition, an exhaust air guide 273 for guidingthe exhaust air from the radiator 41 downward so as to prevent the hotair from colliding on the fuel tank 40 is disposed rearwardly of theradiator 41. Further, an air guide wall 58 a by which the exhaust airguided downward by the exhaust air guide 273 is guided further downwardand rearward is provided at a front end portion of the under cover 58.Forward extension sections 58 p, 58 p (only reference sign 58 p on thedepth side of the drawing is shown) are provided at left and right sidesof the under cover 58, forwardly of the air guide wall 58 a. Betweenthese forward extension sections 58 p, 58 p, an exhaust opening 274 isprovided which is opened to permit the exhaust air from the radiator 41to flow downward of the under cover 58.

The exhaust opening 274 is provided rearwardly of the rear end of therearward extension section 51 b of the front lower cover 51, permittingthe space on the upper side of the rearward extension section 51 b andthe space on the lower side of the rearward extension section 51 b tocommunicate with each other.

FIG. 7 is an essential part sectional view showing the radiator 41, thefuel tank 40 and the surroundings thereof.

Between the fuel tank 40 and the radiator 41, the exhaust air guide 273is provided as a heat insulating guide, which covers a part of the frontwall 40 d of the fuel tank 40 so as to avoid thermal influence of theexhaust air warmed by the radiator 41. Between the exhaust air guide 273and the front wall 40 d of the fuel tank 40, a fresh air passage 278 isformed that is provided with a predetermined clearance CL1 ranging fromthe upper end 273 c to the lower end 273 a of the exhaust air guide 273and through which fresh air flows.

In side view, the front wall 40 d of the fuel tank 40 is obliquelyinclined rearwardly downward. Besides, in side view, the exhaust airguide 273 is curved to be rearwardly protuberant along the front wall 40d of the fuel tank 40, and the air guide wall 58 a is curved to beforwardly protuberant.

As above-mentioned, the fresh air passage 278 is formed to ensure thatfresh air, not mixed with the exhaust air coming from the radiator 41,flows from above the radiator 41 downward along the front wall 40 d ofthe fuel tank 40. This structure ensures that even in the conditionwhere the temperature inside the body cover C is high, a flow of freshair along the front wall 40 d of the fuel tank 40 can be formed and,therefore, the fuel tank 40 can be appropriately air cooled.

The upper end 273 c of the exhaust air guide 273 is disposed below theupper end 41 e of the radiator 41 and above the vertically centralposition of the radiator 41, and the lower end 273 a of the exhaust airguide 273 is provided above the lower end 41 f of the radiator 41 andbelow the vertically central position of the radiator 41.

The exhaust air guide 273 has an intermediate wall 273 d at avehicle-width-directionally central portion thereof. The lower end 273 aof the intermediate wall 273 d and the upper end 58 b of the air guidewall 58 a are disposed proximate to each other. The lower end 273 a ofthe exhaust air guide 273 is located above a horizontal line 275 passingthrough the lower end 41 f of the radiator 41, while the upper end 58 bof the air guide wall 58 a is located below the horizontal line 275.

FIG. 8 is an essential part sectional view showing a front lower portionof the motorcycle 1.

First, positional relationship between the air guide wall 58 a and theexhaust air guide 273 will be described.

The under cover 58 is provided with the air guide wall 58 a, whichextends on the rear side of the radiator 41 while curving forward andupward. The upper end 58 b of this air guide wall 58 a and the lower end273 a of the exhaust air guide 273 are disposed proximate to each otherin the vertical direction (height direction). Between the upper end 58 bof the air guide wall 58 a and the lower end 273 a of the exhaust airguide 273, a gap 276 having a predetermined clearance CL2 is formed.

In the related art, a louver has been provided at a slit-like opening ofan exhaust air passage for the purpose of restraining muddy water or thelike splashed by the front wheel from entering the inside of the bodycover. In this embodiment, on the other hand, the air guide wall 58 aand the exhaust air guide 273 are arranged proximate to each other. Thisarrangement ensures that the exhaust air passage 293 (described indetail later) can be defined by the air guide wall 58 a and the exhaustair guide 273, while restraining intrusion of water or the like by theair guide wall 58 a and the exhaust air guide 273.

In addition, the upper end 58 b of the air guide wall 53 a (morespecifically, the upper end 53 b of the front surface 58 c of the airguide wall 58 a) is disposed rearwardly of the lower end 273 a of theexhaust air guide 273 (more specifically, the lower end 273 a of thefront surface 273 b of the intermediate wall 273 d of the exhaust airguide 273).

Now, a lift-up support part 297 of the front lower cover 51 will bedescribed below.

In order to lift up a vehicle body front portion by a jack or the like,the lift-up support part 297 is provided at a front lower portion of thevehicle body. The lift-up support part 297 includes: a lower crossmember stay 264 which is fixed to a front end lower portion of the frontcross member 17 and is formed with a bottom surface (specifically, abottom surface of a lower plate part 264 a) along an upper surface 51 qof the rearward extension section 51 b of the front lower cover 51; abody cover fixing part 51 r formed for fixing the front lower cover 51to the bottom surface of the lower cross member stay 264; and thelift-up part 51 p provided for putting a lifting-up device such as ajack into contact with the body cover fixing part 51 r.

The body cover fixing part 51 r includes the rearward extension section51 b, a fastening hole 51 s bored in a rear portion of the rearwardextension section 51 b, the lower plate part 264 a of the lower crossmember stay 264, a through-hole 264 b bored in the lower plate part 264a, and a fastening member 298 inserted into the fastening hole 51 s andthe through-hole 264 b from below.

The fastening member 298 includes a head part 298 a, a screw 298 bdriven into the head part 298 a from below, and a plurality of radiallyexpandable pieces 298 c extending from the head part 298 a along theprojecting direction of the screw 298 b and radially expanded by thescrew 298 b.

At the time of inserting the fastening member 298 s into the fasteninghole 51 s and the through-hole 264 b, the radially expandable pieces 298c are radially reduced against their elastic forces, and are passedthrough the fastening hole 51 s and the through-hole 264 b. Thereafter,the screw 298 b is driven through the head part 298 a from below andforced into the inside of the plurality of radially expandable pieces298 c, whereby the radially expandable pieces 298 c are radiallyexpanded as shown, to function as come-off preventive means.

The lift-up part 51 p includes: a stepped part 51 t crank-shaped insection that is formed at a rear end portion of the rearward extensionsection 51 b so as to be bent downward and then extend rearward; and aplurality of lower ribs 51 n and a plurality of upper ribs 51 u that areformed respectively at a lower surface 51 m and an upper surface 51 q ofthe rearward extension section 51 b so as to intersect the stepped part51 t. Specifically, the lower ribs 51 n and the upper ribs 51 u, whichextend in the vehicle longitudinal direction (front-rear direction) areconnected to the stepped part 51 t, and the fastening member 298 isdisposed forwardly of the stepped part 51 t.

The step of the stepped part 51 t is greater than the thickness of thehead part 298 a. Therefore, even when the jack or the like is put intocontact with the lower ribs 51 n from below, the jack or the like wouldnot interfere with the head part 298 a. In addition, as shown in FIG.15, the stepped part 51 t is formed to extend in the vehicle widthdirection.

In FIG. 8, the lower ribs 51 n are formed at the lower surface 51 m ofthe rearward extension section 51 b so as to project downward over therange from a vehicle-longitudinally intermediate portion to the rear endof the rearward extension section 51 b and to extend in the vehiclelongitudinal direction. The upper ribs 51 u are formed at the uppersurface 51 q of the rearward extension section 51 b so as to projectupward over the range from the front end to the rear end of the rearwardextension section 51 b and to extend in the vehicle longitudinaldirection.

On the front side of the stepped part 51 t, the rearward extensionsection 51 b is so inclined as to be located at an upper position as onegoes rearward.

As above-mentioned, the rearward extension section 51 b of the frontlower cover 51 serves as a fixing part for fixing the lower end of thefront lower cover 51 to the body frame F and as the lift-up part 51 pfor lifting up the vehicle body front portion by a jack or the like.Therefore, it is possible to reduce the number of component parts, toreduce the number of assembly steps and to reduce cost, as compared withthe case where a lift-up part is formed especially. In addition, therearward extension section 51 b is molded integrally with the cover body51 a, which also contributes to a reduction in cost.

FIG. 9 shows illustrations of the exhaust air guide 273, wherein FIG. 9Ais a front view, FIG. 9B is a view taken along arrow B in FIG. 9A, andFIG. 9C is a view taken along arrow C in FIG. 9A.

As shown in FIG. 9A, the exhaust air guide 273 is a component part thathas a roughly rectangular profile. The exhaust air guide 273 includes:left and right longitudinal wall parts 273L and 273R extending in thevertical direction and in the vehicle longitudinal direction (theface-back direction of the drawing); an intermediate wall 273 d providedbetween the longitudinal wall parts 273L and 273R; and outer walls 273 eand 273 f provided respectively on the outer sides of the longitudinalwall parts 273L and 273R.

As shown in FIG. 9B, the longitudinal wall parts 273L and 273R areformed to project forward from the intermediate wall 273 d. Thelongitudinal wall parts 273L and 273R and the intermediate wall 273 dtogether form a flattened U-shape in section, and form an exhaust airpassage for guiding the exhaust air coming from the radiator 41 (seeFIG. 6). The longitudinal wall parts 273L and 273R are formed thereinwith hollow parts (cavities) 273 g and 273 h. Incidentally, referencesigns 277 denote bolts made to penetrate the outer walls 273 e and 273 ffor the purpose of fastening the exhaust air guide 273 to the left andright down tubes 13, 13 (see FIG. 5).

As shown in FIG. 5C, the exhaust air guide 273 is right-angledtriangular in side view. The front ends 273 m and 273 n (only referencesign 273 m on the viewer's side is shown) of the longitudinal wall parts273L and 273R (only reference sign 273L on the viewer's side is shown)extend substantially vertically. Each of the outer walls 273 e and 273 f(only reference sign 273 e on the viewer's side is shown) is inclinedrectilinearly in such a manner that its lower end is located rearwardlyof its upper end.

FIG. 10 shows illustrations of the under cover 58, wherein FIG. 10A is aperspective view as viewed from an upper side, FIG. 10B is a perspectiveview as viewed from a lower side, and FIG. 10C is a plan view.

In FIG. 10A, the under cover 58 includes: a flat part 58 e formed torange from a vehicle-longitudinally central portion to a rear portion;the air guide wall 58 a extending from the front end of the flat part 58e while being curved forwardly upward; side edge parts 58 f and 58 gprovided (in a rising state) at left and right side portions of both theflat part 58 e and the air guide wall 58 a; and a plurality ofreinforcement ribs 58 j, 58 j and 58 k, 58 k extending in the vehiclelongitudinal direction over the range from an upper surface of the flatpart 58 e to an upper surface of the air guide wall 58 a.

The side edge parts 58 f and 58 g are provided at front and rearportions thereof with frame mounting parts 58 m and 58 n that areprojected upward and serve for mounting the under cover 58 to thehorizontal extension sections 71, 71 (see FIG. 3) of the left and rightdown tubes 13, 13 (see FIG. 3). In addition, the side edge parts 58 fand 58 g are provided at their front end portions with the left andright forward extension sections 58 p, 58 p extending forward, onvehicle-width-directionally outer sides of the air guide wall 58 a.

Of the plurality of ribs 58 j, 58 j and 58 k, 58 k, the two ribs 58 k,58 k on the inner side extend to the upper end of the air guide wall 58a.

As shown in FIG. 10B, the forward extension section 58 p is formed at afront end portion of each of the left and right side edge parts 58 f and58 g. The left and right forward extension sections 58 p, 53 p and theair guide wall 58 a are interconnected respectively through connectionwalls 58 q (only reference sign 58 q on one side is shown).

As shown in FIG. 10C, the side edge parts 58 f and 58 g inclusive of theleft and right forward extension sections 58 p, 58 p protrude forwardand rearward as compared with the flat part 58 e and the air guide wall58 a. The side edge parts 58 f and 58 g are formed in a forwardlynarrowed shape such that the left and right edges of front end portionsthereof are located on the vehicle-width-directionally inner sides ascompared with the left and right edges of rear end portions thereof. Theside edge parts 58 f and 58 g are integrally formed at rear end sideportions thereof with barb ribs 58 w, 58 x projecting sideways. The barbribs 58 w and 58 x are parts for preventing muddy water or the likesplashed from entering the inside of the body cover C. The rear end 58 rof the under cover 58 is a part which includes: left and right obliqueedges 58 s, 58 s; and a base edge 58 t interconnecting the oblique edges58 s, 58 s. The rear end 58 r is a part formed for avoiding interferencewith the link members 27 (see FIG. 15).

FIG. 11 is an essential part front view of the motorcycle 1, with thebody cover C removed.

The radiator 41 includes the left tank section 41L and the right tanksection 41R that are provided on the left and right sides, and a coresection 41C that is provided between the left tank section 41L and theright tank section 41R.

The left tank section 41L and the right tank section 41R are sectionsfor temporarily holding cooling water. The core section 41C includes aplurality of tubes serving as cooling water passages for circulation ofcooling water between the left tank section 41L and the right tanksection 41R, and cooling fins provided between the tubes. Incidentally,reference sign 38 denotes a muffler.

The left tank section 41L and the right tank section 41R are disposedforwardly of the left and right down tubes 13, 13, respectively. Theleft-right width of the core section 41C is roughly the same as thedistance between respective inside ends of the left and right down tubes13, 13 and as the left-right width of the fuel tank 40.

FIG. 12 is an essential part front view of the motorcycle 1.

The front lower cover 51 constituting the body cover C includes: aradiator opening section 51A composed of a plurality of openings forguiding airflow to the radiator 41; and a fuel tank opening section 51Bfor guiding airflow to a tank extension section 40 k, which extendsupward to above the upper end 41 e of the radiator 41, of the fuel tank40.

The radiator opening section 51A includes a first opening 51 c, a secondopening 51 d, and a third opening 51 e that are arranged in this orderfrom the upper side, and left and right fourth openings 51 f, 51 flocated on the lower side of the third opening 51 e. The fuel tankopening section 51B includes an upper opening 51 g formed in a laterallyelongated shape in an upper portion of the front lower cover 51, and anupper edge opening 279 formed at the upper edge 51 h of the front lowercover 51. The upper edge opening 279 is defined by a cutout 51 jprovided at the upper edge 51 h of the front lower cover 51 and a cutout50 d formed in a front portion of the front cover 50. Incidentally,reference sign 51 k denotes a horn cutout formed in the front lowercover 51 for avoiding interference with a horn 281.

FIG. 13 is a perspective view showing the body frame F and thesurroundings thereof.

The fuel tank 40 is disposed inside a front portion of the body frame F.A front-side part of the fuel tank 40 is covered by the exhaust airguide 273 and the air guide wall 58 a of the under cover 58.

The exhaust air guide 273 is configured as follows. Lower portions ofthe left and right outer walls 273 e and 273 f located on thevehicle-width-directionally outer sides of the longitudinal wall parts273L and 273R are attached to front surfaces of the downward extensionsections 70, 70 of the down tubes 13, 13 by bolts 277, 277. In addition,upper portions of the outer walls 273 e and 273 f, more specifically,insertion parts 273 p, 273 p provided respectively at the upper portionsof the outer walls 273 e and 273 f, are inserted into inserted pieces282 being L-shaped in section that are provided respectively on thedownward extension sections 70, 70. In this way, the exhaust air guide273 is locked to the down tubes 13, 13.

The under cover 58 is configured as follows. The frame mounting parts 58m and 58 n provided respectively on the left and right side edge parts58 f and 58 g (only reference sign 58 g on the viewer's side is shown)are mounted to the lower cross member side brackets 265 of the frontcross member 17 and to the power unit support sections 85 of the downtubes 13 by bolts 266 and bolts 268, respectively. Especially, theforward extension sections 58 p, 58 p of the side edge parts 58 f and 58g are fastened to the lower cross member side brackets 265 provided atlower portions of the front cross member 17. Incidentally, referencesign 43 denotes a canister by which fuel vapor in the fuel tank 40 istemporarily adsorbed and is released into a suction system.

FIG. 14 is an essential part right side view of the motorcycle 1 fromwhich a part of the body cover C has been removed.

A water supply port 284 is attached to an upper end portion of the righttank section 41R of the radiator 41 through a water filling pipe 110.The reservoir tank 46 disposed on a lateral side of the first bentsection 73 of the down tube 13 is connected to the water supply port 284through a reservoir tubing 111. The reservoir tubing 111 is held by ahose holding part 273 q provided at the exhaust air guide 273.Incidentally, reference sign 37 denotes an exhaust pipe connected to anexhaust port at a lower surface of the cylinder head 32. The exhaustpipe 37 extends rearward while passing under the engine E, and isconnected to the muffler 38 (see FIG. 11). Reference sign 286 denotes awater pump provided at the crankcase 30 of the engine E. A pump-sidelower hose 289, which is connected to a lower pipe 263A (see FIG. 5) onthe radiator 41 side, and a return hose 288, which is connected to anupper portion of the cylinder 31 and through which cooling water isreturned from inside the cylinder 31 to the water pump 286, areconnected to the water pump 286. Incidentally, reference sign 285denotes a radiator cap attached to the water supply port 284.

FIG. 15 is an essential part bottom view of a bottom portion of themotorcycle 1.

The front lower cover 51 is disposed rearwardly of the front wheel 2,and the front lower cover 51 is covered with the front floor skirts 56,56 on both lateral sides thereof. The under cover 58 is disposedrearwardly of the rearward extension section 51 b of the front lowercover 51, and the rear floor skirts 57, 57 are disposed on both sides ofthe under cover 58. Vehicle-width-directional gaps 283, 283 forming airpassages are provided between the under cover 58 and the rear floorskirts 57, 57, in bottom view.

Of the rearward extension section 51 b of the front lower cover 51, thepart having the plurality of lower ribs 51 n provided at the lowersurface 51 m to extend in the vehicle longitudinal direction constitutesthe lift-up part 51 p to which a lack or the like is applied at the timeof lifting up a front portion of the motorcycle 1. Left and right edgeportions of the under cover 58 and inside edge portions of the rearfloor skirts 57, 57 are spaced apart in the vehicle width direction todefine the gaps 283, 283 therebetween. Air inside the body cover C isexhausted through the gaps 283, 283. Thus, the under cover 58 and thebody cover C surrounding the under cover 58 define a gap therebetween,along the whole end portions. The left and right front floor skirts 56,56 define gaps 269, 269 between the under cover 58 and themselves. Airinside the body cover C is exhausted through these gaps 269, 269.

FIG. 16 is an essential part bottom view of a vehicle body frontportion.

The radiator 41 is so arranged that the lower end of its core section41C is fastened to a lower bracket 257, which is provided on the frontcross member 17 and extends in the vehicle width direction, by two bolts291, 291. A core section stay 41 h extending upward from the upper endof the core section 41C is fastened to an upper bracket 255 of the frontupper cross member 16 by one bolt 292.

The water filling pipe 110 is connected to the right tank section 41R ofthe radiator 41, and the water supply port 284 is connected to the upperend of the water filling pipe 110.

Furthermore, one end of the reservoir tubing 111 is connected to thewater supply port 284, and the reservoir tank 46 is connected to theother end of the reservoir tubing 111.

The left tank section 41L of the radiator 41 is provided with a lowerhose connection port 41 a and an upper hose connection port 41 b. Alower radiator hose 261 is connected to the lower hose connection port41 a, and an upper radiator hose 262 is connected to the upper hoseconnection port 41 b.

The front cross member 17 and the air guide wall 58 a of the under cover58 define an exhaust air passage 293 (for the radiator 41) on the rearside of the radiator 41. The lower end of the exhaust air passage 293constitutes the exhaust opening 274 provided in an area that is forwardof the air guide wall 58 a and is between the left and right forwardextension sections 58 p, 58 p.

The left and right down tubes 13, 13 are interconnected by the frontcross member 17 extending while being curved so as to project to thefront side of the down tubes 13, 13, in an area that is below theradiator 41 and above the forward extension sections 58 p, 58 p. Thefront cross member 17 (specifically, left and right end portions of thefront cross member 17) overlaps with the forward extension sections 58p, 58 p in bottom view.

Besides, in bottom view, the radiator 41 is disposed between front endportions 16 a and 17 a that are formed as respective parts of the frontupper cross member 16 and the front cross member 17 so as to extend inthe vehicle with direction. This ensures that the upper bracket 255 andthe core section stay 41 h on the front upper cross member 16 side andthe lower bracket 257 on the front cross member 17 side, which membersserve for supporting the radiator 41, can be made roughly the same inlength in the vehicle longitudinal direction. If the radiator supportmember(s) on the front upper cross member 16 side and the radiatorsupport member(s) on the front cross member 17 side are different inlength, the longer radiator support member(s) must be enhanced instrength and rigidity by thickening or the like. This results inincreases in cost and weight due to the use of a special componentpart(s). In this embodiment, on the other hand, the radiator supportmember(s) on the front upper cross member 16 side and the radiatorsupport member(s) on the front cross member 17 side are roughly the samein length. This promises reductions in cost and weight.

FIG. 17 is an essential part sectional view of a vehicle body frontportion.

The exhaust air guide 273 is provided at its left and right portionswith the longitudinal wall parts 273L and 273R projecting forward. Thefront ends 273 m and 273 n of the longitudinal wall parts 273L and 273Rare located rearwardly of the radiator 41, and the exhaust air passage293 is provided between the longitudinal wall parts 273L and 273R.Therefore, the exhaust air from the radiator 41 is restrained fromflowing to the vehicle-width-directionally outer sides beyond thelongitudinal wall parts 273L and 273R.

The lower radiator hose 261 and the upper radiator hose 262 are disposedon the vehicle-width-directionally outer side of the left-sidelongitudinal wall part 273L. Since the lower radiator hose 261 and theupper radiator hose 262 are not provided in the exhaust air passage 293,therefore, these hoses do not influence the exhaust air from theradiator 41.

The vehicle-width-directionally outer end portions 41 m and 41 n of theleft tank section 41L and the right tank section 41R are located on thevehicle-width-directionally outer sides in relation to the longitudinalwall parts 273L and 273R in plan view.

The longitudinal wall parts 273L and 273R are so formed as to havehollow parts (cavities) 273 g and 273 h therein. The reservoir tubing111 is held by the hose holding part 273 q, which is roughly angularU-shaped in section and is provided on the outer side of thelongitudinal wall part 273R on the vehicle-width-directionally rightside.

The reservoir tank 46 is a vehicle-longitudinally elongated vesseldisposed proximate to and on the right side of the body frame F. Anoutside surface 46 a of a front portion of the reservoir tank 46 is soinclined as to be located on the vehicle-width-directionally more innerside on the front side than on the rear side. This ensures that at thetime of covering the reservoir tank 46 with the body cover C (see FIG.15) (specifically, the rear floor skirt 57 (see FIG. 15)) on the outerside, the body cover C can be disposed on thevehicle-width-directionally more inner side while forming it in aforwardly narrowed shape. Therefore, aerodynamic characteristics can beenhanced and downsizing of the vehicle body can be promised.

The electric motor 272 disposed rearwardly of the radiator 41 is mountedto the respective rear surfaces of the left tank section 41L and theright tank section 41R of the radiator 41 by bolts 296, through aplurality of motor stays 294 (only one reference sign 294 is shown).

FIG. 18 is a sectional view of a left lower portion of the vehicle bodyfront portion, showing the positional relationship between the left-siderear floor skirt 57 and the under cover 58. Specifically, an inner edge57 a on the vehicle-width-directionally inner side of the rear floorskirt 57 and a left edge 58 v of the under cover 58 are spaced apart inthe vehicle width direction. Air inside the body cover C is exhaustedthrough a gap 283 formed between the inner edge 57 a and the left edge58 v. The clearance of the gap 283 is CL3. A gap 283 having a clearanceof CL3 is formed also between an inner edge on thevehicle-width-directionally inner side of the right-side rear floorskirt 57 (see FIG. 15) and a right edge of the under cover 58. Thus, theunder cover 58 and the left and right rear floor skirts 57, 57 are notinterconnected. The under cover 58 is fixed to the body frame F, whilethe rear floor skirts 57 are fixed to the body frame F and the stepfloors 68 (see FIG. 1). The step floors 68 are fixed to the left andright step frames 23L, 23R (reference sign 23L is shown in FIGS. 2, and23R in FIG. 14).

The gaps 283 between the rear floor skirts 57 and the under cover 58 areopening in the vertical direction, and their clearance CL3 is small.Therefore, even if muddy water or the like is splashed from the roadsurface, the muddy water or the like would not easily enter the insideof the body cover. Also, the muddy water or the like can be preventedfrom entering the inside from lateral sides.

FIG. 19 is a sectional view taken along line XIX-XIX of FIG. 15.

The barb rib 58 w projecting sideways is formed at a rear end side partof the under cover 58. The rear floor skirt 57 is formed with a skirtrecess part 57 b (which is dogleg-shaped in section) so as to face thebarb rib 58 w on the vehicle-width-directionally outer side of the barbrib 58 w. The barb rib 58 w and the skirt recess part 57 b form acutwater labyrinth 295 for preventing muddy water or the like fromentering the inside of the body cover. Specifically, the skirt recesspart 57 b includes a lower wall 57 d having a lower edge located underthe barb rib 58 w, and an upper wall 57 e extending from the upper edgeof the lower wall 57 d to the upper side of the barb rib 58 w. The lowerwall 57 d, the barb rib 58 w, and the upper wall 57 e in this order fromthe lower side form a maze structure, namely, labyrinth. Therefore,muddy water or the like splashed from the road surface can be preventedfrom externally entering the inside of the rear floor skirt 57 and theunder cover 58, without interconnecting the under cover 58 and the rearfloor skirt 57. Besides, as shown in FIGS. 10(C) and 15, the cutwaterlabyrinth 295 is provided only in the areas where the barb ribs 58 w and58 x of the under cover 58 are formed. This configuration is forreducing the influence of the muddy water or the like on accessoriessuch as the air cleaner box 35 (see FIG. 1) disposed rearwardly of theunder cover 58. Thus, the cutwater labyrinth 295 is provided at the gapbetween each side rear edge part of the under cover 58 and each rearfloor skirt 57. This ensures that the exhaust air passing inside thebody cover C can be exhausted, while effectively preventing intrusion ofmuddy water or the like.

Now, flows of air in the surroundings of the fuel tank 40 and theradiator 41 as above-mentioned will be described below.

FIG. 20 is an operation diagram illustrating the flows of air inside thebody cover.

Air flowing in from the vehicle body front side through the fuel tankopening section 51B, specifically, through the upper edge opening 279and the upper opening 51 g, to the rear side of the front lower cover 51flows down from an upper front side of the front wall 40 d along thefront wall 40 d, as indicated by arrows A01, A02, and A1. Further, theair flows down through a fresh air passage 278 formed between the frontwall 40 d and the intermediate wall 273 d of the exhaust air guide 273,as indicated by arrows A2 and A3. Furthermore, as indicated by arrow A4,the air passes between a lower portion of the front wall 40 d and theair guide wall 58 a of the under cover 58, and flows rearward betweenthe fuel tank 40 and the under cover 58.

In addition, as indicated by arrows A5 to A8, airflow passing from thevehicle body front side through the radiator opening section 51A of thefront lower cover 51, specifically, through the first opening 51 c, thesecond opening 51 d, the third opening 51 e, and the fourth openings 51f, 51 f (only one reference sign 51 f is shown) and flowing to the rearside of the front lower cover 51 passes across the core section 410 ofthe radiator 41 to the rear side of the radiator 41. Further, it passesdownward along the front surface of the intermediate wall 273 d of theexhaust air guide 273. Then, as indicated by arrow A9, the airflowpasses through an exhaust air passage 293 formed forwardly of the airguide wall 58 a, and goes out to the lower side of the under cover 58via the exhaust opening 274, which is an outlet of the exhaust airpassage 293.

As above-mentioned, in this embodiment, the fresh air and the radiatorexhaust air are separated from each other to form two layers of flow, byutilizing the exhaust air guide 273 and the air guide wall 58 a of theunder cover 58, between the fuel tank 40 and the radiator 41. As aresult, a thermal influence of the radiator exhaust air is preventedfrom being imposed on the fuel tank 40. Besides, the radiator exhaustair can be efficiently discharged, while arranging the fuel tank 40 andthe radiator 41 proximate to each other.

The radiator 41 is disposed on the lower side of the fuel tank 40 havingits front wall 40 d inclined forward. Therefore, even though the exhaustair guide 273, the fan 271, and the electric motor 272 are disposed inthe space (triangular in side view) between the fuel tank 40 and theradiator 41 while the space between the upper end of the radiator 41 andthe front wall 40 d is secured, it is possible to set the fuel tank 40and the radiator 41 proximate to each other. Moreover, it is possible toform two layers of air passages, namely, the exhaust air passage 293 andthe fresh air passage 278.

FIG. 21 is an operation diagram illustrating the flow of exhaust airfrom the radiator 41.

As indicated by arrows, airflow impinging on the radiator 41 from thevehicle front side passes across the radiator 41, to become exhaust airwarmed by the radiator 41. The warm exhaust air is collected into theexhaust air passage 293 surrounded by the intermediate wall 273 d andthe left and right longitudinal wall parts 273L and 273R of the exhaustair guide 273 covering the front side of the fuel tank 40, and goesdownward, to be discharged to the lower side of the body cover C.Therefore, the exhaust air from the radiator 41 is restrained fromflowing out to the vehicle-width-directionally outer sides of thelongitudinal wall parts 273L and 273R. Accordingly, thermal influence ofthe exhaust air on the fuel tank 40 can be reduced. In addition, thelower radiator hose 261 and the upper radiator hose 262 are disposed onthe vehicle-width-directionally outer side of the longitudinal wallparts 273L and 273R. Therefore, the lower radiator hose 261 and theupper radiator hose 262 do not traverse the exhaust air passage 293.This permits the exhaust air to flow smoothly.

FIG. 22 is an operation diagram illustrating the flow of air inside alower portion of the body cover C.

The air flowing rearward inside the body cover C, specifically, betweenthe lower surface of the fuel tank 40 (see FIG. 19) and the under cover58, is fresh air which has been mixed little with the exhaust air fromthe radiator 41 (see FIG. 19). As indicated by arrow, this fresh air isdischarged to the exterior of the body cover C through the gaps 283formed between the left edge 58 v and the right edge (not shown) of theunder cover 58 and the inner edges 57 a of the rear floor skirts 57, 57(only one reference sign 57 is shown). Each of the gaps 283 is opened inthe vertical direction, and has a narrow clearance. Further, since thefresh air flows out through the gaps 283, muddy water or the likesplashed from the front wheel 2 (see FIG. 1) is not liable to enter thegaps 283 from below.

Now, operation of the above-mentioned lift-up support part 297 will bedescribed below.

FIG. 23 is an operation diagram illustrating the operation of thelift-up support part 297 of the front lower cover 51.

In the case of lifting up a vehicle body front portion for maintenanceor the like, a jack 290 is disposed under the lift-up part 51 p providedat a front lower portion of the vehicle body. The jack 290 includes acylinder section 290 a, and a rod section 290 b provided in the cylindersection 290 a so that it can be moved up and down. By operating anoperating section (not shown), the rod section 290 b can be raisedrelative to the cylinder section 290 a by a hydraulic pressure,pneumatic pressure or the like. Incidentally, reference sign 290 cdenotes a base section attached to the lower end of the cylinder section290 a. The base section 290 c is placed on the ground.

By operating the operating section of the jack 290, the rod section 290b is raised, as indicated by void arrow, whereby the upper end of therod section 290 b is brought into contact with the lift-up part 51 p ofthe vehicle body. Then, the rod section 290 b is further raised, to liftup the vehicle body to a desired height position. In this instance, theweight of the vehicle body front portion acts on the lift-up supportpart 297. The weight can be supported by both the lower cross memberstay 264 mounted to the front cross member 17 and the rearward extensionsection 51 b of the front lower cover 51 attached to the lower crossmember stay 264.

FIG. 24 is an operation diagram illustrating the operation of thestepped part 51 t of the rearward extension section 51 b of the frontlower cover 51.

A water drop 299 splashed by the front wheel may adhere to the lowersurface 51 m of the rearward extension section 51 b of the front lowercover 51. In such a case, airflow passing as indicated by void arrowcauses the water drop 299 to move on the lower surface 51 m toward thevehicle body rear side, as indicated by arrow a1. At the stepped part 51t, the water drop 299 moves down the surface of the stepped part 51 t asindicated by arrow a2, and falls as indicated by arrow a3. Therefore,the water drop 299 can be prevented from moving upward through theexhaust opening 274, which is disposed rearwardly of the rear end of therearward extension section 51 b, to enter the inside of the body coverC.

As shown in FIGS. 1 and 6, a fuel tank 40 and radiator 41 layoutstructure is provided for the motorcycle 1 as a saddle type vehiclewherein the seat 10 is disposed rearwardly of the handlebar 25, thecenter tunnel 250 is provided under an area between the handlebar 25 andthe seat 10, the left and right step floors 68, 68 (only reference sign68 on the viewer's side is shown) for the driver's feet are disposed onthe left and right sides of the center tunnel 250, and the fuel tank 40and the radiator 41 located forwardly of the fuel tank 40 are disposedinside the center tunnel 250. In the layout structure, the front wall 40d of the fuel tank 40 is inclined forward so as to obliquely extenddownwardly rearward from the upper end thereof. The radiator 41 isdisposed on a rear and lower side of the front end 40 h of the fuel tank40.n addition, the radiator 41 is provided vertically or is forwardlyinclined so that its lower end 41 f is located rearwardly of its upperend 41 e in side view. The forward inclination angle of the front wall40 d of the fuel tank 40 relative to the vertical is greater than theforward inclination angle of the radiator 41 relative to the vertical.

According to this configuration, the radiator 41 is disposed on the rearand lower side of the front end 40 h of the fuel tank 40. Therefore, thefuel tank 40 and the radiator 41 can be disposed proximate to eachother. Besides, a space for passage of exhaust air can be secured on therear side of the radiator 41. This makes it possible to make themotorcycle 1 smaller in size and compact in the vehicle longitudinaldirection, while securing an enhanced cooling efficiency of the radiator41.

The forward inclination angle of the front wall 40 d of the fuel tank 40relative to the vertical is greater above the upper end position of theradiator 41 than below the upper end position. Therefore, the upper end41 e of the radiator 41 may be disposed proximate to the position wherethe forward inclination angle of the fuel tank 40 changes, whileincreasing the fuel tank capacity in an area above the upper endposition of the radiator 41. This ensures that the fuel tank 40 and theradiator 41 can be disposed to be more proximate to each other, and themotorcycle 1 can be made smaller in size and compact in the vehiclelongitudinal direction.

Besides, as shown in FIGS. 2 and 6, the head pipe 12 for turnablysupporting the steering system 260 is provided at a front portion of thebody frame F, and the upper end 40 j of the fuel tank 40 is disposedabove the lower end of the head pipe 12. This ensures that the fuel tankcapacity can be secured by elongating the fuel tank 40 in an upwarddirection. Therefore, the radiator 41 can be disposed proximate to thefuel tank 40 while making the fuel tank 40 compact in the vehiclelongitudinal direction. Consequently, the motorcycle 1 can be madefurther smaller in size and compact in its longitudinal direction.

As shown in FIGS. 2, 4 and 5, the body frame F has a configurationwherein the pair of left and right down tubes 13, 13 each include: thedownward extension section 70 extending downwardly rearward from thehead pipe 12; the first bent section 73 as a bent section which is bentrearward in the vicinity of a lower portion of the fuel tank 40; and thehorizontal extension section 71 as a rearward extension sectionextending rearward from the first bent section 73. The front wall 40 dof the fuel tank 40 is located forwardly of the downward extensionsections 70 of the down tubes 13, 13, in side view. Therefore, the fueltank 40 and the radiator 41 can be disposed on the more front side inthe motorcycle 1. This enables effective utilization of the space on therear side of the fuel tank 40.

In addition, the fuel tank 40 is supported by upper portions of thedownward extension sections 70 of the down tubes 13, 13. Therefore,stays or the like for fixing the fuel tank 40 to the down tubes 13, 13can be made shorter.

As shown in FIGS. 2, 3 and 5, the front cross member 17 as a lower crossmember that interconnects the left and right first bent sections 73, 73and extends so as to protrude forward relative to the down tubes 13, 13,is provided. Also, the front upper cross member 16 as an upper crossmember interconnects the left and right downward extension sections 70,70 on the upper side of the radiator 41 and extends so as to protrudeforward relative to the down tubes 13, 13, is provided. The radiator 41is fixed to the front cross member 17 and the front upper cross member16. Therefore, the radiator 41 can be disposed forwardly of the downtubes 13, 13. This ensures that the vehicle as a whole can be madecompact, by disposing the radiator 41 and the fuel tank 40 close to thefront wheel 2.

Besides, the lower end 41 f of the radiator 41 is disposed above thefirst bent sections 73. This makes it possible to arrange the radiator41 at a higher position, and thereby to permit airflow to impinge on theradiator 41 without being affected by the front wheel 2 and the likedisposed forwardly of the radiator 41. Consequently, cooling efficiencyof the radiator 41 can be enhanced.

As shown in FIGS. 2, 5 and 17, a radiator hose layout structure isprovided for the motorcycle 1 as a saddle type vehicle that includes:the radiator 41 disposed rearwardly of the front wheel 2; the fuel tank40 disposed rearwardly of the radiator 41; the exhaust air guide 273provided between the radiator 41 and the fuel tank 40 so as to guide theexhaust air from the radiator 41; the unit swing engine U as awater-cooled power unit arranged rearwardly of the fuel tank 40; and thelower radiator hose 261 and the upper radiator hose 262 as radiatorhoses that are connected respectively to the radiator 41 and the unitswing engine U so as to circulate cooling water. In the radiator hoselayout structure, the longitudinal wall parts 273L and 273R projectingforward are provided at vehicle-width-directionally end portions of theexhaust air guide 273. The front ends 273 m and 273 n of thelongitudinal wall parts 273L and 273R are provided rearwardly of theradiator 41. Besides, the exhaust air passage 293 permitting the exhaustair from the radiator 41 to flow therethrough is provided between thelongitudinal wall parts 273L and 273R. The lower radiator hose 261 andthe upper radiator hose 262 are arranged on thevehicle-width-directionally outer side of the longitudinal wall parts273L and 273R.

According to this configuration, the lower radiator hose 261 and theupper radiator hose 262 are not disposed inside the exhaust air passage293. Therefore, the exhaust air from the radiator 41 can be let flowsmoothly into the exhaust air passage 293, and cooling efficiency of theradiator 41 can be thereby enhanced.

In the related art, the radiator hoses are disposed inside an exhaustair guide. Therefore, the exhaust air guide must be detached at the timeof assembly or maintenance of the radiator hoses. Thus, the layoutstructure in the related art has demanded much labor at the time ofassembly or maintenance of the radiator hoses. In this embodiment, onthe other hand, the cooling water tubings including the lower radiatorhose 261 and the upper radiator hose 262, as well as the lower pipe 263Aand the upper pipe 263B connected to the lower radiator hose 261 and theupper radiator hose 262, respectively, are concentrated on thevehicle-width-directionally outer and left side of the exhaust air guide273. This makes it possible to enhance the assembleability andmaintainability of the cooling water tubings.

The radiator 41 is provided, on vehicle-width-directionally left andright sides thereof, with the left tank section 41L and the right tanksection 41R as tank sections. The core section 41C including a coolingwater passage and cooling fins is provided between the left and righttank sections 41L and 41R. The vehicle-width-directionally outer endportions of the core section 41C are disposed on thevehicle-width-directionally outer sides relative to the longitudinalwall parts 273L and 273R in plan view. This ensures that the coresection 41C, necessary for cooling, fronts on the area between thelongitudinal wall parts 273L and 273R. Therefore, even with the lowerradiator hose 261 and the upper radiator hose 262 arranged on thevehicle-width-directionally outer side relative to the longitudinal wallparts 273L and 273R, cooling efficiency of the radiator 41 can beprevented from being lowered. In addition, at the time of connecting thelower radiator hose 261 and the upper radiator hose 262 to the left tanksection 41L, the longitudinal wall part 273L does not obstruct theoperation, so that workability can be enhanced.

As shown in FIGS. 11 and 17, the lower radiator hose 261 and the upperradiator hose 262 are connected to the left tank section 41L on thevehicle-width-directionally one side. The water supply port 284 isprovided on the upper side of the right tank section 41R on thevehicle-width-directionally other side. The reservoir tubing 111, as areservoir tank hose for interconnecting the water supply port 284 andthe reservoir tank 46 for reserving cooling water, is held by the hoseholding part 273 q. This hose holding part 273 q is provided at a sideend portion of the exhaust air guide 273 on thevehicle-width-directionally outer side of the longitudinal wall part273R on the vehicle-width-directionally other side. Therefore, the lowerradiator hose 261 and the upper radiator hose 262 as well as thereservoir tubing 111 can be arranged compactly, while being distributedrespectively to both sides of the radiator 41. Besides, since thereservoir tubing 111 is held by the hose holding part 273 q of theexhaust air guide 273, it is unnecessary to provide an especial hoseholding part. Consequently, it is possible to reduce the number ofcomponent parts and the number of assembly steps, to reduce cost, and toenhance productivity.

In addition, since the longitudinal wall parts 273L and 273R are formedtherein with the hollow parts (cavities) 273 g and 273 h, it is possibleto enhance rigidity of the longitudinal wall parts 273L and 273R whilelightening the longitudinal wall parts 273L and 273R. Consequently, thelongitudinal wall parts 273L and 273R can be greatly elongated forward.

As shown in FIGS. 2, 13 and 17, the left and right down tubes 13, 13,which extend downward from the head pipe 12 turnably supporting thesteering system 260 and constituting a front portion of the body frameF, are provided. Besides, the outer walls 273 e and 273 f, as bothlateral end portions provided on the vehicle-width-directionally outersides relative to the longitudinal wall parts 273L and 273R of theexhaust air guide 273, are fixed to the front surfaces of the down tubes13, 13. Thus, the fixing parts for fixing the exhaust air guide 273 tothe down tubes 13, 13 are not provided inside the exhaust air passage293. This makes it possible to cause the exhaust air from the radiator41 to flow smoothly into the exhaust air passage 293, and thereby toenhance cooling efficiency of the radiator 41. In addition, since theexhaust air guide 273 is fixed to the front surfaces of the down tubes13, 13, the force exerted on the exhaust air guide 273 by the exhaustair can be efficiently transmitted to the down tubes 13, 13. Therefore,lightening of the exhaust air guide 273 can be contrived.

As shown in FIG. 7, in side view, the upper end 273 c of the exhaust airguide 273 is provided below the upper end 41 e of the radiator 41 andabove the vertically central position of the radiator 41. Besides, thelower end 273 a of the exhaust air guide 273 is provided above the lowerend 41 f of the radiator 41 and below the vertically central position ofthe radiator 41. Therefore, the exhaust air guide 273 is provided in aposition where the exhaust air from the radiator 41 is concentrated.This makes it possible to define the exhaust air passage 293 by theexhaust air guide 273, while forming the exhaust air guide 273 in asmaller and compact form, thereby reducing cost and weight.

As shown in FIGS. 1, 2, 6, 12 and 20, an air guide structure is providedfor the motorcycle 1 as a saddle type vehicle that includes: the headpipe 12 turnably supporting the steering system 260 and constituting afront portion of the body frame F; the seat 10 disposed rearwardly ofthe head pipe 12; the center tunnel 250 provided between the head pipe12 and the seat 10; the step floors 68 provided on the left and rightsides of the center tunnel 250; the fuel tank 40 disposed inside thecenter tunnel 250; and the radiator 41 disposed forwardly of the fueltank 40 inside the center tunnel 250.n the air guide structure, the fueltank 40 is formed with the tank extension section 40 k extending upwardto above the upper end 41 of the radiator 41. The front wall 40 d of thetank extension section 40 k is forwardly inclined to extend rearwardlydownward. The front lower cover 51 is disposed forwardly of the radiator41 and rearwardly of the front wheel 2. The front lower cover 51 isprovided with the radiator opening section 51A for guiding airflow tothe radiator 41, and the fuel tank opening section 51B for guiding theairflow to the fuel tank 40 inclusive of the tank extension section 40k.

According to this configuration, the front lower cover 51 is providedwith the fuel tank opening section 51B, separately from the radiatoropening section 51A. This ensures that by introducing airflow via thefuel tank opening section 51B to the fuel tank 40, fresh air other thanthe radiator exhaust air can be guided to an area between the radiator41 and the fuel tank 40, through utilization of the front wall 40 d ofthe tank extension section 40 k. Therefore, the influence of the exhaustair from the radiator 41 on the fuel tank 40 can be reduced effectively.

As shown in FIGS. 6 and 7, between the fuel tank 40 and the radiator 41,the exhaust air guide 273 as a heat insulating guide is provided thatcovers a part of the front wall 40 d of the fuel tank 40 so as toprevent the exhaust air from the radiator 41 from thermally influencingthe fuel tank 40. Between the exhaust air guide 273 and the fuel tank40, the predetermined clearance CL1 is provided over the range from theupper end 273 c to the lower end 273 a of the exhaust air guide 273.Thus, instead of simply covering the front wall 40 d of the fuel tank40, the predetermined clearance CL1 is provided between the exhaust airguide 273 and the fuel tank 40. This ensures that airflow introduced byway of the front lower cover 51 is guided to the area between theexhaust air guide 273 and the fuel tank 40. As a result, aheat-insulating effect can be enhanced, and thermal influence on thefuel tank 40 can be further reduced.

The upper end 273 c of the exhaust air guide 273 is disposed below theupper end 41 e of the radiator 41 and above the vertically centralposition of the radiator 41. If, for example, the exhaust air guide 273is disposed above the upper end 41 e of the radiator 41, the clearancebetween the radiator 41 and the fuel tank 40 must be enlarged, since thefront wall 40 d of the fuel tank 40 is inclined forward. In contrast,when the upper end of the exhaust air guide 273 is disposed below theupper end 41 e of the radiator 41, the spacing between the radiator 41and the fuel tank 40 can be made smaller. This ensures that the vehiclecan be made compact in the vehicle longitudinal direction.

In addition, since the upper end 273 c of the exhaust air guide 273 isdisposed below the upper end 41 e of the radiator 41, the exhaust airfrom the radiator 41 may be considered to flow from the upper end 41 eof the exhaust air guide 273 into the gap between the exhaust air guide273 and the fuel tank 40. In this embodiment, however, the upper end 273c of the exhaust air guide 273 is provided above the vertically centralposition of the radiator 41. Therefore, the fresh air (other than theexhaust air from the radiator 41) introduced via the gap between theupper end 41 e of the radiator 41 and the fuel tank 40 ensures that theexhaust air from the radiator 41 can be restrained from flowing via theupper end 273 c of the exhaust air guide 273 into the gap between theexhaust air guide 273 and the fuel tank 40. Consequently, it is possibleto minimize the influence of the exhaust air from the radiator 41 on thefuel tank 40.

Further, with the upper end 273 c of the exhaust air guide 273 disposedbelow the upper end 41 e of the radiator 41, it is possible to reducethe clearance between the upper end 41 e of the radiator 41 and the fueltank 40. This contributes to making the vehicle compact. In addition,this configuration makes it possible to enhance the flow velocity of thefresh air passing through the clearance between the upper end 41 e ofthe radiator 41 and the fuel tank 40. Therefore, it is made easier toguide the fresh air into the clearance CL1 between the exhaust air guide273 and the fuel tank 40.

As shown in FIGS. 9, 17 and 21, the exhaust air guide 273 is provided,on vehicle-width-directionally both sides thereof, with the left andright longitudinal wall parts 273L and 273R as longitudinal fin partsprojecting forward. As a result of this, the exhaust air from theradiator 41 is restrained from flowing to thevehicle-width-directionally outer sides relative to the longitudinalwall parts 273L and 273R. Therefore, the exhaust air from the radiator41 can be collected to the vehicle-width-directionally inner side of thelongitudinal wall parts 273L and 273R. As a result, the thermalinfluence of the exhaust air from the radiator 41 on the fuel tank 40can be suppressed more effectively.

In addition, as shown in FIGS. 6 and 8, the lower side of the fuel tank40 is covered with the under cover 58. The under cover 58 is providedwith the air guide wall 58 a extending toward the radiator 41 side. Theupper end 58 b of the air guide wall 58 a and the lower end 273 a of theexhaust air guide 273 are disposed proximate to each other in thevertical direction. Therefore, a radiator exhaust air passage (exhaustair passage 293) with a large area can be defined by the air guide wall58 a and the exhaust air guide 273, while restraining water and the likefrom intruding through the gap between the air guide wall 58 a and theexhaust air guide 273. The air guide wall 58 a and the exhaust air guide273 cooperate with each other to ensure that the exhaust air from theradiator 41 can be made to flow from the rear side of the radiator 41along the respective front surfaces 273 b and 58 c of the exhaust airguide 273 and the air guide wall 58 a, to be discharged to the lowerside of the under cover 58. Besides, the back surfaces of the exhaustair guide 273 and the air guide wall 58 a, the fresh air can be made toflow to the side of the lower surface of the fuel tank 40. Thus,introduced air can be distributed into front and rear two layers offlow, with the exhaust air guide 273 and the air guide wall 58 a as aboundary. The one-side layer of flow contributes to discharge of theexhaust air coming from the radiator 41, whereas the other-side layer offlow contributes to heat insulation by the fresh air. Both of thesefunctions make it possible to reduce the thermal influence on the fueltank 40 more effectively.

As shown in FIGS. 15, 18 and 22, the rear floor skirts 57, 57 as underside covers are provided on the vehicle-width-directionally both sidesof the under cover 58. The outside ends (the left edge 58 v and theright edge (not shown) as vehicle-width-directional outer edges) of theunder cover 58 and the inside ends (the inner edges 57 a asvehicle-width-directionally inner edges) of the rear floor skirts 57 arespaced from each other. Therefore, the fresh air guided by the air guidewall 58 a into the gap between the under cover 58 and the lower surfaceof the fuel tank 40 can be discharged via the gaps between the undercover 58 and the rear floor skirts 57, whereby a flow rate of the freshair can be secured. Consequently, thermal influence on the fuel tank 40can be reduced further effectively.

In addition, as shown in FIGS. 10(A) to 10(C) and 19, the outside ends(specifically, the barb ribs 58 w, 58 x) of the under cover 58 and theinside ends (specifically, the lower walls 57 d) of the rear floorskirts 57 are so disposed as to overlap with each other in the verticaldirection. Therefore, it is possible to reduce the possibility of asituation in which water or the like splashed by the front wheel 2 (seeFIG. 1) might enter the inside of the under cover 58 and the rear floorskirts 57 from below the vehicle body, since the outside ends of theunder cover 58 and the inside ends of the rear floor skirts 57 arevertically spaced from each other.

As shown in FIGS. 1, 2, 5 and 7, a radiator exhaust structure isprovided for the motorcycle 1 as a saddle type vehicle that includes: ahead pipe 12 turnably supporting the steering system 260 andconstituting a front portion of the body frame F; the seat 10 disposedrearwardly of the head pipe 12; the center tunnel 250 provided under anarea between the head pipe 12 and the seat 10; the step floors 68provided on the left and right sides of the center tunnel 250; theradiator 41 disposed in the center tunnel 250; the exhaust air guide 273provided rearwardly of the radiator 41 to guide the exhaust air from theradiator 41; and the under cover 58 by which the vehicle is covered onthe lower side thereof. In the radiator exhaust structure, the air guidewall 58 a constituting the front end of the under cover 58 and extendingforwardly upward is disposed rearwardly of the radiator 41. Beside, theupper end 58 b of the air guide wall 58 a and the lower end 273 a of theexhaust air guide 273 are disposed proximate to each other in thevertical direction.

According to this configuration, the upper end 58 b of the air guidewall 58 a and the lower end 273 a of the exhaust air guide 273 aredisposed proximate to each other. This ensures that the exhaust airpassage 293 with a large area can be defined by the air guide wall 58 aand the exhaust air guide 273, while restraining water and the like fromintruding via the gap between the air guide wall 58 a and the exhaustair guide 273. The air guide wall 58 a and the exhaust air guide 273cooperate with each other to cause the exhaust air from the radiator 41to flow down from the rear side of the radiator 41 along the exhaust airguide 273 and the air guide wall 58 a, to be efficiently discharged tothe lower side of the under cover 58. Consequently, cooling efficiencyof the radiator 41 can be enhanced.

As shown in FIGS. 8 and 10, the predetermined clearance CL2 is formedbetween the upper end 58 b of the air guide wall 58 a and the lower end273 a of the exhaust air guide 273. On the vehicle-width-directionallyboth end sides of the air guide wall 58 a at the front end of the undercover 58, forward extension sections 58 p, 58 p are formed as left andright extension sections extending forward. In addition, the connectionwall 58 q interconnecting the forward extension sections 58 p, 58 p andthe air guide wall 58 a is formed. The air guide wall 58 a and theexhaust air guide 273 are formed proximate to each other, with thepredetermined clearance CL2 therebetween, so that they are notinterconnected. Therefore, a step for assembling the air guide wall 58 aand the exhaust air guide 273 together inside the body cover C can beabolished, and productivity can be enhanced thereby. Besides, therigidity of the air guide wall 58 a can be secured by the connectionwall 58 q connected to the forward extension sections 58 p, withoutinterconnecting the air guide wall 58 a and the exhaust air guide 273.

In addition, the ribs 58 j and 58 k extending in the vehiclelongitudinal direction are provided at the upper surface of the airguide wall 58 a. As a result, the rigidity of the air guide wall 58 acan be further enhanced by the ribs 58 j and 58 k.

As shown in FIGS. 2, 5 and 16, the radiator 41 is disposed forwardly ofthe down tubes 13, 13 provided as the left and right frame membersobliquely extending downwardly rearward from the head pipe 12. The frontcross member 17 is provided as a cross member by which the down tubes13, 13 as left and right frame members are interconnected below theradiator 41 and above the forward extension sections 58 p, 58 p and thatextends so as to project forward. The front cross member 17 overlapswith the forward extension sections 58 p, 58 p in plan view. Thisensures that the exhaust air from the radiator 41 can be restrained bythe front cross member 17 from impinging directly on the forwardextension sections 58 p, 58 p. Therefore, it is possible to reducerigidity of the forward extension sections 58 p, 58 p themselves andthereby to lighten the under cover 58. Further, since the exhaust airdoes not impinge on the forward extension sections 58 p, 58 p,disturbance of the flow of the exhaust air can be restrained.

In addition, as shown in FIGS. 5 and 13, the front cross member 17 isprovided with the lower cross member side brackets 265, 265 as fixingparts for fixing the forward extension sections 58 p, 58 p. Therefore,the under cover 58 is fixed by the forward extension sections 58 p, 58p, which are close to the air guide wall 58 a, whereby rigidity of theair guide wall 58 a can be enhanced.

As shown in FIGS. 6 and 16, the exhaust opening 274 so opened as topermit the exhaust air from the radiator 41 to flow therethrough to thelower side of the under cover 58 is provided on the front side of theair guide wall 58 a and between the left and right forward extensionsections 58 p, 58 p. Therefore, the exhaust air from the radiator 41 iseffected through the exhaust opening 274 defined by the front end of theunder cover 58. This ensures that an exhaust space with a large area canbe formed in a concentrated manner, without being dispersed.Consequently, cooling efficiency of the radiator 41 can be enhanced.

In addition, as shown in FIG. 8, the upper end 58 b of the front surface58 c of the air guide wall 58 a is disposed rearwardly of the lower end273 a of the front surface 273 b of the exhaust air guide 273.Therefore, in the case where the predetermined clearance CL2 in thevertical direction is provided between the upper end 58 b of the airguide wall 58 a and the lower end 273 a of the exhaust air guide 273, itis possible, by disposing the upper end 58 b of the front surface 58 cof the air guide wall 58 a rearwardly of the lower end 273 a of thefront surface 273 b of the exhaust air guide 273, to cause the exhaustair to effectively flow downward along the front surface 58 c of the airguide wall 58 a, while restraining the exhaust air from entering theinside of the air guide wall 58 a via the clearance CL2.

As shown in FIGS. 6 and 7, the fuel tank 40 is provided rearwardly ofthe exhaust air guide 273, and the front wall 40 d of the fuel tank 40is obliquely inclined rearwardly downward. The exhaust air guide 273 iscurved to be protuberant rearward in side view, and the lower end 273 aof the exhaust air guide 273 is disposed above the lower end 41 f of theradiator 41. The air guide wall 58 a is curved to be protuberantforward, and the upper end 58 b of the air guide wall 58 a is disposedbelow the lower end 41 f of the radiator 41. Therefore, with the exhaustair guide 273 curved to be protuberant rearward, it is ensured that eventhough the radiator 41 is disposed forwardly of the fuel tank 40, theexhaust air can be efficiently guided downward, while forming a largerexhaust air space by the exhaust air guide 273. The exhaust air guideddownward from the radiator 41 can be discharged rearward with a largearea while utilizing the space under the fuel tank 40, by the air guidewall 58 a curved to be protuberant forward.

As shown in FIGS. 2, 3, 5, 8 and 23, a lift-up support part structure isprovided for the motorcycle 1 as a saddle type vehicle wherein the leftand right down tubes 13, 13 obliquely extend downwardly rearward fromthe head pipe 12 turnably supporting the steering system 260; respectivefront lower portions of the down tubes 13, 13 are interconnected as aleft-right pair by the front cross member 17 provided as a cross member;the front lower cover 51 as a body cover is disposed at least under thefront cross member 17; and the lift-up part 51 p to which a lifting-updevice such as the jack 290 is to be applied at the time of lifting upthe vehicle body is provided at a vehicle body lower portion. Thelift-up support part structure includes: the lower cross member stay 264as a stay fixed to the front cross member 17 so as to form at least abottom surface along the surface of the front lower cover 51; the bodycover fixing part 51 r for fixing the front lower cover 51 to the bottomsurface of the lower cross member stay 264; and the lift-up part 51 pprovided at the body cover fixing part 51 r.

According to the just-mentioned configuration, the lower cross memberstay 264 for fixing the front lower cover 51 to the front cross member17 is provided. This makes it possible to maintain the mutual positionalrelationship between the front cross member 17 and the front lower cover51. Besides, the part for securing the strength and rigidity on thefront lower cover 51 side can be minimized near the lower cross memberstay 264, and the weight of the front lower cover 51 can be restrainedfrom being increased.

As shown in FIGS. 2 and 8, the body cover includes the front lower cover51 disposed rearwardly of the front wheel 2. The front lower cover 51has the rearward extension section 51 b as a lower surface section ofwhich the lower end extends to the lower side of the front cross member17 on the rear side. The rearward extension section 51 b has a rear endlocated rearwardly of the lift-up part 51 p. Therefore, the position ofthe lift-up part 51 p can be easily confirmed by the operator. Besides,the body cover fixing part 51 r can be provided at an end portion of therearward extension section 51 b, so that the front lower cover 51 can befirmly fixed. In addition, since thickening of the front lower cover 51and the like are unnecessitated, lightening of the front lower cover 51can be promised. Besides, even when the front lower cover 51 is thinnedand lightened, the presence of the body cover fixing part 51 r makes itpossible to maintain the shape of the front lower cover 51.

As shown in FIGS. 8, 15 and 24, the exhaust opening 274 as an openingthrough which the space above the rearward extension section 51 b andthe space below the rearward extension section 51 b communicate witheach other is provided rearwardly of the rear end of the rearwardextension section 51 b. In addition, the stepped part 51 t formed in acrank-like shape with an offset to the lower side is provided at a rearend portion of the rearward extension section 51 b, and the stepped part51 t extends in the vehicle width direction. With the crank-shapedstepped part 51 t thus provided, the rigidity of the front lower cover51 can be enhanced over the vehicle width direction. Besides, when waterdrop or the like adheres to the surface of the rearward extensionsection 51 b of the front lower cover 51 and the water drop or the likeflows rearward on the surface of the rearward extension section 51 b,the water drop or the like can be dropped by the stepped part 51 t. Thisensures that even through the exhaust opening 274 is provided rearwardlyof the front lower cover 51, the water drop and the like can beprevented from entering the inside of the body cover C, inclusive of thefront lower cover 51, via the exhaust opening 274.

As shown in FIG. 8, the upper surface 51 q and the lower surface 51 m ofthe rearward extension section 51 b are formed respectively with theupper ribs 51 u and the lower ribs 51 n as pluralities of ribs extendingin the vehicle longitudinal direction. The upper ribs 51 u and the lowerribs 51 n are connected to the stepped part 51 t. Therefore, therigidity of the lift-up part 51 p can be enhanced by the stepped part 51t as well as the upper ribs 51 u and the lower ribs 51 n. For a certainlevel of rigidity, the lift-up part 51 p can be reduced in weight ascompared with a structure wherein the lift-up part 51 p is increased inmaterial thickness so as to enhance rigidity.

Besides, the body cover fixing part 51 r is fixed from the lower side ofthe front lower cover 51 by the fastening member 293 or the engagementmember, and the fastening member 298 or the engagement member isdisposed forwardly of the stepped part 51 t. This ensures that evenwhere the fastening member 298 or the engagement member is assembledfrom the lower side of the front lower cover 51, the head part 298 a ofthe fastening member 298 or the engagement member can be prevented bythe stepped part 51 t from projecting to the lower side of the bodycover fixing part 51 r. Consequently, contact between the lifting-updevice and the head part 298 a can be restrained.

As shown in FIGS. 8 and 23, the rearward extension section 51 b is soinclined that it is located at an upper position as one goes rearward,on the front side of the stepped part 51 t. This ensures that at thetime of lifting up a vehicle front portion, the vehicle front portion islifted up in such a manner that the rearward extension section 51 bapproaches a horizontal state. At the time of lifting, therefore, theweight can be efficiently transmitted to the lifting-up device. Besides,the lower ribs 51 n formed at the lower surface 51 m of the rearwardextension section 51 b can be formed to be increased in verticalthickness toward the rearward direction. This leads to a furtherenhancement of the rigidity of the lift-up part 51 p.

The above-described embodiment is merely one mode for carrying out thepresent invention, and arbitrary modifications and applications arepossible within the scope of the gist of the invention.

The saddle type vehicle to which the present invention is to be appliedincludes not only motorcycles (inclusive of motorbikes) but alsothree-wheel vehicles and four-wheel vehicles which are classified asATVs (all terrain vehicles).

DESCRIPTION OF REFERENCE SYMBOLS

-   1 Motorcycle (Saddle type vehicle)-   2 Front wheel-   10 Seat-   12 Head pipe-   40 Fuel tank-   40 d Front wall of fuel tank-   40 k Tank extension section-   41 Radiator-   41 e Upper end of radiator-   51 Front lower cover-   51A Radiator opening section-   51B Fuel tank opening section-   57 Rear flower skirt (Under side cover)-   58 Under cover-   58 a Air guide wall-   58 b Upper end of air guide wall-   68 Step floor-   250 Center tunnel-   260 Steering system-   273 Exhaust air guide (Heat insulation guide)-   273 a Lower end of exhaust air guide-   273 c Upper end of exhaust air guide-   273L, 273R Longitudinal wall part (Longitudinal fin part)-   F Body frame

What is claimed is:
 1. An air guide structure for a saddle type vehicleincluding a head pipe turnably supporting a steering system andconstituting a front portion of a body frame, a seat disposed rearwardlyof the head pipe, a center tunnel provided between the head pipe and theseat, step floors provided on the left and right sides of the centertunnel, a fuel tank disposed in the center tunnel, and a radiatordisposed forwardly of the fuel tank in the center tunnel, wherein thefuel tank is provided with a tank extension section that extends toabove an upper end of the radiator, a front wall of the tank extensionsection is inclined forward by obliquely extending rearwardly downward,a front lower cover is disposed forwardly of the radiator and rearwardlyof a front wheel, and the front lower cover is provided with a radiatoropening section for guiding airflow to the radiator and with a fuel tankopening section for guiding the airflow to the fuel tank inclusive ofthe tank extension section.
 2. The air guide structure according toclaim 1, wherein a heat insulation guide that covers a part of the frontwall of the fuel tank to avoid thermal influence of the exhaust air fromthe radiator is provided between the fuel tank and the radiator, and apredetermined clearance is provided between the heat insulation guideand the fuel tank over a range from an upper end to a lower end of theheat insulation guide.
 3. The air guide structure according to claim 2,wherein the upper end of the heat insulation guide is disposed below theupper end of the radiator and above a vertical-directionally centralposition of the radiator.
 4. The air guide structure according to claim2, wherein the heat insulation guide is provided with longitudinal finparts projecting forward, on vehicle-width-directionally both sides, soas to restrain exhaust air from the radiator from flowing tovehicle-width-directionally outer sides of the longitudinal fin parts.5. The air guide structure according to claim 1, wherein the fuel tankis covered with an under cover on the lower side thereof, the undercover is provided with an air guide wall extending toward the radiatorside, and an upper end of the air guide wall and a lower end of the heatinsulation guide are disposed proximate to each other in the verticaldirection.
 6. The air guide structure according to claim 5, wherein theupper end of the air guide wall and the lower end of the heat insulationguide is disposed with a predetermined clearance therebetween.
 7. Theair guide structure according to claim 5, wherein under side covers areprovided on vehicle-width-directionally both sides of the under cover,and the outside ends of the under cover and the inside ends of the underside covers are disposed separate from each other.
 8. The air guidestructure according to claim 7, wherein the outside ends of the undercover and the inside ends of the under side covers are so disposed as tooverlap with each other in plan view.
 9. The air guide structureaccording to claim 3, wherein the heat insulation guide is provided withlongitudinal fin parts projecting forward, onvehicle-width-directionally both sides, so as to restrain exhaust airfrom the radiator from flowing to vehicle-width-directionally outersides of the longitudinal fin parts.
 10. The air guide structureaccording to claim 2, wherein the fuel tank is covered with an undercover on the lower side thereof, the under cover is provided with an airguide wall extending toward the radiator side, and an upper end of theair guide wall and a lower end of the heat insulation guide are disposedproximate to each other in the vertical direction.
 11. The air guidestructure according to claim 10, wherein the upper end of the air guidewall and the lower end of the heat insulation guide is disposed with apredetermined clearance therebetween.
 12. The air guide structureaccording to claim 3, wherein the fuel tank is covered with an undercover on the lower side thereof, the under cover is provided with an airguide wall extending toward the radiator side, and an upper end of theair guide wall and a lower end of the heat insulation guide are disposedproximate to each other in the vertical direction.
 13. The air guidestructure according to claim 12, wherein the upper end of the air guidewall and the lower end of the heat insulation guide is disposed with apredetermined clearance therebetween.
 14. The air guide structureaccording to claim 4, wherein the fuel tank is covered with an undercover on the lower side thereof, the under cover is provided with an airguide wall extending toward the radiator side, and an upper end of theair guide wall and a lower end of the heat insulation guide are disposedproximate to each other in the vertical direction.
 15. The air guidestructure according to claim 14, wherein the upper end of the air guidewall and the lower end of the heat insulation guide is disposed with apredetermined clearance therebetween.
 16. The air guide structureaccording to claim 6, wherein under side covers are provided onvehicle-width-directionally both sides of the under cover, and theoutside ends of the under cover and the inside ends of the under sidecovers are disposed separate from each other.
 17. The air guidestructure according to claim 16, wherein the outside ends of the undercover and the inside ends of the under side covers are so disposed as tooverlap with each other in plan view.